Borislav Petkov [Tue, 26 Oct 2010 18:24:03 +0000 (20:24 +0200)]
perf: Start the restructuring
mv kernel/perf_event.c -> kernel/events/core.c. From there, all further
sensible splitting can happen. The idea is that due to perf_event.c
becoming pretty sizable and with the advent of the marriage with ftrace,
splitting functionality into its logical parts should help speeding up
the unification and to manage the complexity of the subsystem.
Steven Rostedt [Thu, 28 Apr 2011 01:43:36 +0000 (21:43 -0400)]
ftrace: Consolidate updating of ftrace_trace_function
There are three locations that perform almost identical functions in order
to update the ftrace_trace_function (the ftrace function variable that gets
called by mcount).
Consolidate these into a single function called update_ftrace_function().
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Steven Rostedt [Tue, 26 Apr 2011 20:11:03 +0000 (16:11 -0400)]
ftrace: Move record update for normal and modules into a separate function
The updating of a function record is moved to a single function. This will allow
us to add specific changes in one location for both modules and kernel
functions.
Later patches will determine if the function record itself needs to be updated
(which enables the mcount caller), or just the ftrace_ops needs the update.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Steven Rostedt [Mon, 25 Apr 2011 18:32:42 +0000 (14:32 -0400)]
ftrace: Remove FTRACE_FL_CONVERTED flag
Since we disable all function tracer processing if we detect
that a modification of a instruction had failed, we do not need
to track that the record has failed. No more ftrace processing
is allowed, and the FTRACE_FL_CONVERTED flag is pointless.
The FTRACE_FL_CONVERTED flag was used to denote records that were
successfully converted from mcount calls into nops. But if a single
record fails, all of ftrace is disabled.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Steven Rostedt [Fri, 22 Apr 2011 03:16:46 +0000 (23:16 -0400)]
ftrace: Remove FTRACE_FL_FAILED flag
Since we disable all function tracer processing if we detect
that a modification of a instruction had failed, we do not need
to track that the record has failed. No more ftrace processing
is allowed, and the FTRACE_FL_FAILED flag is pointless.
Removing this flag simplifies some of the code, but some ftrace_disabled
checks needed to be added or move around a little.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Steven Rostedt [Fri, 22 Apr 2011 02:59:12 +0000 (22:59 -0400)]
ftrace: Remove failures file
The failures file in the debugfs tracing directory would list the
functions that failed to convert when the old dead ftrace daemon
tried to update code but failed. Since this code is now dead along
with the daemon the failures file is useless. Remove it.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Steven Rostedt [Fri, 22 Apr 2011 02:41:35 +0000 (22:41 -0400)]
ftrace: Remove unnecessary disabling of irqs
The disabling of interrupts around ftrace_update_code() was used
to protect against the evil ftrace daemon from years past. But that
daemon has long been killed. It is safe to keep interrupts enabled
while updating the initial mcount into nops.
The ftrace_mutex is also held which keeps other users at bay.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Steven Rostedt [Sat, 30 Apr 2011 02:35:33 +0000 (22:35 -0400)]
ftrace: Only update the function code on write to filter files
If function tracing is enabled, a read of the filter files will
cause the call to stop_machine to update the function trace sites.
It should only call stop_machine on write.
Cc: stable@kernel.org Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> # /tmp/build-perf/perf stat -- sleep 1
> Error: stalled-cycles-frontend event is not supported.
> Fatal: Not all events could be opened.
>
> This is a Dell R410 with an E5620 processor.
Fail in a softer fashion on unknown/unsupported events.
Reported-by: David Ahern <dsahern@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/n/tip-7y40wib8n006io7hjpn1dsrm@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add two generic hardware events: front-end and back-end stalled cycles.
These events measure conditions when the CPU is executing code but its
capabilities are not fully utilized. Understanding such situations and
analyzing them is an important sub-task of code optimization workflows.
Both events limit performance: most front end stalls tend to be caused
by branch misprediction or instruction fetch cachemisses, backend
stalls can be caused by various resource shortages or inefficient
instruction scheduling.
Front-end stalls are the more important ones: code cannot run fast
if the instruction stream is not being kept up.
An over-utilized back-end can cause front-end stalls and thus
has to be kept an eye on as well.
The exact composition is very program logic and instruction mix
dependent.
We use the terms 'stall', 'front-end' and 'back-end' loosely and
try to use the best available events from specific CPUs that
approximate these concepts.
Use the UOPS_EXECUTED.*,c=1,i=1 event on Intel CPUs - it is a rather
good indicator of CPU execution stalls, more sensitive and more inclusive
than the 0xa2 resource stalls event (which does not count nearly as many
stall types).
Don Zickus [Wed, 27 Apr 2011 10:32:33 +0000 (06:32 -0400)]
perf, x86, nmi: Move LVT un-masking into irq handlers
It was noticed that P4 machines were generating double NMIs for
each perf event. These extra NMIs lead to 'Dazed and confused'
messages on the screen.
I tracked this down to a P4 quirk that said the overflow bit had
to be cleared before re-enabling the apic LVT mask. My first
attempt was to move the un-masking inside the perf nmi handler
from before the chipset NMI handler to after.
This broke Nehalem boxes that seem to like the unmasking before
the counters themselves are re-enabled.
In order to keep this change simple for 2.6.39, I decided to
just simply move the apic LVT un-masking to the beginning of all
the chipset NMI handlers, with the exception of Pentium4's to
fix the double NMI issue.
Later on we can move the un-masking to later in the handlers to
save a number of 'extra' NMIs on those particular chipsets.
I tested this change on a P4 machine, an AMD machine, a Nehalem
box, and a core2quad box. 'perf top' worked correctly along
with various other small 'perf record' runs. Anything high
stress breaks all the machines but that is a different problem.
Thanks to various people for testing different versions of this
patch.
perf stat: Print out miss/hit ratio for L1 data-cache events
Print out this kind of l1-dcache-misses percentage:
Performance counter stats for './bw_tcp localhost':
29,956,262,201 cycles # 3.002 GHz (scaled from 85.14%)
8,255,209,558 stalled-cycles # 27.56% of all cycles are idle (scaled from 86.56%)
1,206,130,308 l1-dcache-misses # 40.49% of all L1-dcache hits (scaled from 86.30%)
2,978,756,779 l1-dcache-refs # 298.512 M/sec (scaled from 70.02%)
8,861,956,159 instructions # 0.30 insns per cycle
# 0.93 stalled cycles per insn (scaled from 84.27%)
1,644,306,068 branches # 164.782 M/sec (scaled from 86.43%)
74,778,443 branch-misses # 4.55% of all branches (scaled from 70.69%)
9978.695711 task-clock # 0.693 CPUs utilized
The new PERF_COUNT_HW_STALLED_CYCLES event tries to approximate
cycles the CPU does nothing useful, because it is stalled on a
cache-miss or some other condition.
perf events, x86: Work around the Nehalem AAJ80 erratum
On Nehalem CPUs the retired branch-misses event can be completely bogus,
when there are no branch-misses occuring. When there are a lot of branch
misses then the count is pretty accurate. Still, this leaves us with an
event that over-counts a lot.
Detect this erratum and work it around by using BR_MISP_EXEC.ANY events.
These will also count speculated branches but still it's a lot more
precise in practice than the architectural event.
Peter Zijlstra [Tue, 26 Apr 2011 11:24:33 +0000 (13:24 +0200)]
perf, x86: Fix BTS condition
Currently the x86 backend incorrectly assumes that any BRANCH_INSN
with sample_period==1 is a BTS request. This is not true when we do
frequency driven profiling such as 'perf record -e branches'.
Solves this error:
$ perf record -e branches ./array
Error: sys_perf_event_open() syscall returned with 95 (Operation not supported).
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reported-by: Ingo Molnar <mingo@elte.hu> Cc: "Metzger, Markus T" <markus.t.metzger@intel.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/n/tip-rd2y4ct71hjawzz6fpvsy9hg@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ecryptfs/ecryptfs-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ecryptfs/ecryptfs-2.6:
eCryptfs: Flush dirty pages in setattr
eCryptfs: Handle failed metadata read in lookup
eCryptfs: Add reference counting to lower files
eCryptfs: dput dentries returned from dget_parent
eCryptfs: Remove extra d_delete in ecryptfs_rmdir
Eric Paris [Mon, 25 Apr 2011 20:26:29 +0000 (16:26 -0400)]
SELINUX: Make selinux cache VFS RCU walks safe
Now that the security modules can decide whether they support the
dcache RCU walk or not it's possible to make selinux a bit more
RCU friendly. The SELinux AVC and security server access decision
code is RCU safe. A specific piece of the LSM audit code may not
be RCU safe.
This patch makes the VFS RCU walk retry if it would hit the non RCU
safe chunk of code. It will normally just work under RCU. This is
done simply by passing the VFS RCU state as a flag down into the
avc_audit() code and returning ECHILD there if it would have an issue.
Based-on-patch-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that the whole dcache_hash_bucket crap is gone, go all the way and
also remove the weird locking layering violations for locking the hash
buckets. Add hlist_bl_lock/unlock helpers to move the locking into the
list abstraction instead of requiring each caller to open code it.
After all allowing for the bit locks is the whole point of these helpers
over the plain hlist variant.
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
bit_spinlock: don't play preemption games inside the busy loop
When we are waiting for the bit-lock to be released, and are looping
over the 'cpu_relax()' should not be doing anything else - otherwise we
miss the point of trying to do the whole 'cpu_relax()'.
Do the preemption enable/disable around the loop, rather than inside of
it.
Noticed when I was looking at the code generation for the dcache
__d_drop usage, and the code just looked very odd.
After 57db4e8d73ef2b5e94a3f412108dff2576670a8a changed eCryptfs to
write-back caching, eCryptfs page writeback updates the lower inode
times due to the use of vfs_write() on the lower file.
To preserve inode metadata changes, such as 'cp -p' does with
utimensat(), we need to flush all dirty pages early in
ecryptfs_setattr() so that the user-updated lower inode metadata isn't
clobbered later in writeback.
Tyler Hicks [Tue, 15 Mar 2011 19:54:00 +0000 (14:54 -0500)]
eCryptfs: Handle failed metadata read in lookup
When failing to read the lower file's crypto metadata during a lookup,
eCryptfs must continue on without throwing an error. For example, there
may be a plaintext file in the lower mount point that the user wants to
delete through the eCryptfs mount.
If an error is encountered while reading the metadata in lookup(), the
eCryptfs inode's size could be incorrect. We must be sure to reread the
plaintext inode size from the metadata when performing an open() or
setattr(). The metadata is already being read in those paths, so this
adds minimal performance overhead.
This patch introduces a flag which will track whether or not the
plaintext inode size has been read so that an incorrect i_size can be
fixed in the open() or setattr() paths.
For any given lower inode, eCryptfs keeps only one lower file open and
multiplexes all eCryptfs file operations through that lower file. The
lower file was considered "persistent" and stayed open from the first
lookup through the lifetime of the inode.
This patch keeps the notion of a single, per-inode lower file, but adds
reference counting around the lower file so that it is closed when not
currently in use. If the reference count is at 0 when an operation (such
as open, create, etc.) needs to use the lower file, a new lower file is
opened. Since the file is no longer persistent, all references to the
term persistent file are changed to lower file.
Locking is added around the sections of code that opens the lower file
and assign the pointer in the inode info, as well as the code the fputs
the lower file when all eCryptfs users are done with it.
This patch is needed to fix issues, when mounted on top of the NFSv3
client, where the lower file is left silly renamed until the eCryptfs
inode is destroyed.
Call dput on the dentries previously returned by dget_parent() in
ecryptfs_rename(). This is needed for supported eCryptfs mounts on top
of the NFSv3 client.
vfs_rmdir() already calls d_delete() on the lower dentry. That was being
duplicated in ecryptfs_rmdir() and caused a NULL pointer dereference
when NFSv3 was the lower filesystem.
Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev:
libata: ahci_start_engine compliant to AHCI spec
ata: pata_at91.c bugfix for initial_timing initialisation
ata: pata_at91.c bugfix for high master clock
ahci: AHCI-mode SATA patch for Intel Panther Point DeviceIDs
ata_piix: IDE-mode SATA patch for Intel Panther Point DeviceIDs
libata: Pioneer DVR-216D can't do SETXFER
ahci: don't enable port irq before handler is registered
libata: Implement ATA_FLAG_NO_DIPM and apply it to mcp65
libata: Kill unused ATA_DFLAG_{H|D}IPM flags
ahci: EM supported message type sysfs attribute
Merge branch 'for-linus' of git://git.infradead.org/ubifs-2.6
* 'for-linus' of git://git.infradead.org/ubifs-2.6:
UBIFS: fix master node recovery
UBIFS: fix false assertion warning in case of I/O failures
UBIFS: fix false space checking failure
At the end of section 10.1 of AHCI spec (rev 1.3), it states
Software shall not set PxCMD.ST to 1 until it is determined that
a functoinal device is present on the port as determined by
PxTFD.STS.BSY=0, PxTFD.STS.DRQ=0 and PxSSTS.DET=3h
Even though most AHCI host controller works without this check,
specific controller will fail under this condition.
Signed-off-by: Jian Peng <jipeng2005@gmail.com> Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Igor Plyatov [Mon, 28 Mar 2011 12:56:14 +0000 (16:56 +0400)]
ata: pata_at91.c bugfix for initial_timing initialisation
The "struct ata_timing" must contain 10 members, but ".dmack_hold" member was
forgotten for "initial_timing" initialisation. This patch fixes such a problem.
Signed-off-by: Igor Plyatov <plyatov@gmail.com> Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Igor Plyatov [Mon, 28 Mar 2011 12:56:15 +0000 (16:56 +0400)]
ata: pata_at91.c bugfix for high master clock
The AT91SAM9 microcontrollers with master clock higher then 105 MHz
and PIO0, have overflow of the NCS_RD_PULSE value in the MSB. This
lead to "NCS_RD_PULSE" pulse longer then "NRD_CYCLE" pulse and driver
does not detect ATA device.
Signed-off-by: Igor Plyatov <plyatov@gmail.com> Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Jeff Mahoney [Tue, 19 Apr 2011 15:13:32 +0000 (11:13 -0400)]
libata: Pioneer DVR-216D can't do SETXFER
Commit 4a5610a04d415ed94af75bb1159d2621d62c8328 fixed an issue with
the Pioneer DVR-212D not handling SETXFER correctly. An openSUSE user
reported a similar issue with his DVR-216D that the NOSETXFER horkage
worked around for him as well.
This patch adds the DVR-216D (1.08) to the horkage list for NOSETXFER.
The issue was reported at:
https://bugzilla.novell.com/show_bug.cgi?id=679143
Reported-by: Volodymyr Kyrychenko <vladimir.kirichenko@gmail.com> Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Maxime Bizon [Wed, 16 Mar 2011 13:58:32 +0000 (14:58 +0100)]
ahci: don't enable port irq before handler is registered
The ahci_pmp_attach() & ahci_pmp_detach() unmask port irqs, but they
are also called during port initialization, before ahci host irq
handler is registered. On ce4100 platform, this sometimes triggers
"irq 4: nobody cared" message when loading driver.
Fixed this by not touching the register if the port is in frozen
state, and mark all uninitialized port as frozen.
Signed-off-by: Maxime Bizon <mbizon@freebox.fr> Acked-by: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Ben Hutchings [Sat, 23 Apr 2011 17:42:56 +0000 (18:42 +0100)]
kconfig: Avoid buffer underrun in choice input
Commit 40aee729b350 ('kconfig: fix default value for choice input')
fixed some cases where kconfig would select the wrong option from a
choice with a single valid option and thus enter an infinite loop.
However, this broke the test for user input of the form 'N?', because
when kconfig selects the single valid option the input is zero-length
and the test will read the byte before the input buffer. If this
happens to contain '?' (as it will in a mips build on Debian unstable
today) then kconfig again enters an infinite loop.
The dentry hashing rules have been really quite complicated for a long
while, in odd ways. That made functions like __d_drop() very fragile
and non-obvious.
In particular, whether a dentry was hashed or not was indicated with an
explicit DCACHE_UNHASHED bit. That's despite the fact that the hash
abstraction that the dentries use actually have a 'is this entry hashed
or not' model (which is a simple test of the 'pprev' pointer).
The reason that was done is because we used the normal 'is this entry
unhashed' model to mark whether the dentry had _ever_ been hashed in the
dentry hash tables, and that logic goes back many years (commit b3423415fbc2: "dcache: avoid RCU for never-hashed dentries").
That, in turn, meant that __d_drop had totally different unhashing logic
for the dentry hash table case and for the anonymous dcache case,
because in order to use the "is this dentry hashed" logic as a flag for
whether it had ever been on the RCU hash table, we had to unhash such a
dentry differently so that we'd never think that it wasn't 'unhashed'
and wouldn't be free'd correctly.
That's just insane. It made the logic really hard to follow, when there
were two different kinds of "unhashed" states, and one of them (the one
that used "list_bl_unhashed()") really had nothing at all to do with
being unhashed per se, but with a very subtle lifetime rule instead.
So turn all of it around, and make it logical.
Instead of having a DENTRY_UNHASHED bit in d_flags to indicate whether
the dentry is on the hash chains or not, use the hash chain unhashed
logic for that. Suddenly "d_unhashed()" just uses "list_bl_unhashed()",
and everything makes sense.
And for the lifetime rule, just use an explicit DENTRY_RCUACCEES bit.
If we ever insert the dentry into the dentry hash table so that it is
visible to RCU lookup, we mark it DENTRY_RCUACCESS to show that it now
needs the RCU lifetime rules. Now suddently that test at dentry free
time makes sense too.
And because unhashing now is sane and doesn't depend on where the dentry
got unhashed from (because the dentry hash chain details doesn't have
some subtle side effects), we can re-unify the __d_drop() logic and use
common code for the unhashing.
Also fix one more open-coded hash chain bit_spin_lock() that I missed in
the previous chain locking cleanup commit.
vfs: get rid of 'struct dcache_hash_bucket' abstraction
It's a useless abstraction for 'hlist_bl_head', and it doesn't actually
help anything - quite the reverse. All the users end up having to know
about the hlist_bl_head details anyway, using 'struct hlist_bl_node *'
etc. So it just makes the code look confusing.
And the cost of it is extra '&b->head' syntactic noise, but more
importantly it spuriously makes the hash table dentry list look
different from the per-superblock DCACHE_DISCONNECTED dentry list.
As a result, the code ended up using ad-hoc locking for one case and
special helper functions for what is really another totally identical
case in the very same function.
Merge branch 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6
* 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6:
tty/n_gsm: fix bug in CRC calculation for gsm1 mode
serial/imx: read cts state only after acking cts change irq
parport_pc.c: correctly release the requested region for the IT887x
SECURITY: Move exec_permission RCU checks into security modules
Right now all RCU walks fall back to reference walk when CONFIG_SECURITY
is enabled, even though just the standard capability module is active.
This is because security_inode_exec_permission unconditionally fails
RCU walks.
Move this decision to the low level security module. This requires
passing the RCU flags down the security hook. This way at least
the capability module and a few easy cases in selinux/smack work
with RCU walks with CONFIG_SECURITY=y
Signed-off-by: Andi Kleen <ak@linux.intel.com> Acked-by: Eric Paris <eparis@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
ALSA: hda - Fix unused warnings when !SND_HDA_NEEDS_RESUME
ALSA: hda - Add a fix-up for Acer dmic with ALC271x codec
ASoC: add a module alias to the FSI driver
ALSA: emu10k1 - Fix "Music" controls to "Synth" controls in documents
ARM: s3c2440: gta02; Register dfbmcs320 device for BT audio interface
ASoC: codecs: JZ4740: Fix OOPS
ASoC: Fix output PGA enabling in wm_hubs CODECs
ASoC: sn95031: decorate function with __devexit_p()
ASoC: SAMSUNG: Fix the inverted clocks handling for pcm driver
ASoC: sst_platform: Fix lock acquring
ASoC: fsi: driver safely remove for against irq
ASoC: fsi: modify vague PM control on probe
ASoC: fsi: take care in failing case of dai register
MAINTAINERS: Update Samsung ASoC maintainer's id
ASoC: WM8903: HP and Line out PGA/mixer DAPM fixes
ASoC: Set left channel volume update bits for WM8994
ASoC: fix config error path
ASoC: check channel mismatch between cpu_dai and codec_dai
ASoC: Tegra: Suspend/resume support
Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
perf, x86: Update/fix Intel Nehalem cache events
perf, x86: P4 PMU - Don't forget to clear cpuc->active_mask on overflow
x86, perf event: Turn off unstructured raw event access to offcore registers
perf: Support Xeon E7's via the Westmere PMU driver
perf, x86: P4 PMU - Don't forget to clear cpuc->active_mask on overflow
It's not enough to simply disable event on overflow the
cpuc->active_mask should be cleared as well otherwise counter
may stall in "active" even in real being already disabled (which
potentially may lead to the situation that user may not use this
counter further).
Don pointed out that:
" I also noticed this patch fixed some unknown NMIs
on a P4 when I stressed the box".
Tested-by: Lin Ming <ming.m.lin@intel.com> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Acked-by: Don Zickus <dzickus@redhat.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Link: http://lkml.kernel.org/r/1303398203-2918-3-git-send-email-dzickus@redhat.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
x86, perf event: Turn off unstructured raw event access to offcore registers
Andi Kleen pointed out that the Intel offcore support patches were merged
without user-space tool support to the functionality:
|
| The offcore_msr perf kernel code was merged into 2.6.39-rc*, but the
| user space bits were not. This made it impossible to set the extra mask
| and actually do the OFFCORE profiling
|
Andi submitted a preliminary patch for user-space support, as an
extension to perf's raw event syntax:
|
| Some raw events -- like the Intel OFFCORE events -- support additional
| parameters. These can be appended after a ':'.
|
| For example on a multi socket Intel Nehalem:
|
| perf stat -e r1b7:20ff -a sleep 1
|
| Profile the OFFCORE_RESPONSE.ANY_REQUEST with event mask REMOTE_DRAM_0
| that measures any access to DRAM on another socket.
|
But this kind of usability is absolutely unacceptable - users should not
be expected to type in magic, CPU and model specific incantations to get
access to useful hardware functionality.
The proper solution is to expose useful offcore functionality via
generalized events - that way users do not have to care which specific
CPU model they are using, they can use the conceptual event and not some
model specific quirky hexa number.
We already have such generalization in place for CPU cache events,
and it's all very extensible.
"Offcore" events measure general DRAM access patters along various
parameters. They are particularly useful in NUMA systems.
We want to support them via generalized DRAM events: either as the
fourth level of cache (after the last-level cache), or as a separate
generalization category.
That way user-space support would be very obvious, memory access
profiling could be done via self-explanatory commands like:
perf record -e dram ./myapp
perf record -e dram-remote ./myapp
... to measure DRAM accesses or more expensive cross-node NUMA DRAM
accesses.
These generalized events would work on all CPUs and architectures that
have comparable PMU features.
( Note, these are just examples: actual implementation could have more
sophistication and more parameter - as long as they center around
similarly simple usecases. )
Now we do not want to revert *all* of the current offcore bits, as they
are still somewhat useful for generic last-level-cache events, implemented
in this commit:
e994d7d23a0b: perf: Fix LLC-* events on Intel Nehalem/Westmere
But we definitely do not yet want to expose the unstructured raw events
to user-space, until better generalization and usability is implemented
for these hardware event features.
( Note: after generalization has been implemented raw offcore events can be
supported as well: there can always be an odd event that is marginally
useful but not useful enough to generalize. DRAM profiling is definitely
*not* such a category so generalization must be done first. )
Furthermore, PERF_TYPE_RAW access to these registers was not intended
to go upstream without proper support - it was a side-effect of the above e994d7d23a0b commit, not mentioned in the changelog.
As v2.6.39 is nearing release we go for the simplest approach: disable
the PERF_TYPE_RAW offcore hack for now, before it escapes into a released
kernel and becomes an ABI.
Once proper structure is implemented for these hardware events and users
are offered usable solutions we can revisit this issue.
Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
ide: unexport DISK_EVENT_MEDIA_CHANGE for ide-gd and ide-cd
block: don't propagate unlisted DISK_EVENTs to userland
elevator: check for ELEVATOR_INSERT_SORT_MERGE in !elvpriv case too
ide: unexport DISK_EVENT_MEDIA_CHANGE for ide-gd and ide-cd
check_events() implementations in both ide-gd and ide-cd are
inadequate for in-kernel event polling. Both generate media change
events continuously when certain conditions are met causing infinite
event loop between the driver and userland event handler.
As disk event now supports suppression of unlisted events, simply
de-listing DISK_EVENT_MEDIA_CHANGE from disk->events resolves the
problem. Internal handling around media revalidation will behave the
same while userland will fall back to userland event polling after
detecting the device doesn't support disk events.
block: don't propagate unlisted DISK_EVENTs to userland
DISK_EVENT_MEDIA_CHANGE is used for both userland visible event and
internal event for revalidation of removeable devices. Some legacy
drivers don't implement proper event detection and continuously
generate events under certain circumstances. For example, ide-cd
generates media changed continuously if there's no media in the drive,
which can lead to infinite loop of events jumping back and forth
between the driver and userland event handler.
This patch updates disk event infrastructure such that it never
propagates events not listed in disk->events to userland. Those
events are processed the same for internal purposes but uevent
generation is suppressed.
This also ensures that userland only gets events which are advertised
in the @events sysfs node lowering risk of confusion.
elevator: check for ELEVATOR_INSERT_SORT_MERGE in !elvpriv case too
The sort insert is the one that goes to the IO scheduler. With
the SORT_MERGE addition, we could bypass IO scheduler setup
but still ask the IO scheduler to insert the request. This would
cause an oops on switching IO schedulers through the sysfs
interface, unless the disk just happened to be idle while it
occured.
Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, numa: Fix cpu nodemasks for NUMA emulation and CONFIG_DEBUG_PER_CPU_MAPS
Revert "x86, NUMA: Fix fakenuma boot failure"
* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
virtio: console: Enable call to hvc_remove() on console port remove
virtio_pci: Prevent double-free of pci regions after device hot-unplug
virtio: Decrement avail idx on buffer detach
Merge branch 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6
* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
agp: fix arbitrary kernel memory writes
agp: fix OOM and buffer overflow
drm/radeon/kms: fix IH writeback on r6xx+ on big endian machines
Merge branch 'drm-intel-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/keithp/linux-2.6
* 'drm-intel-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/keithp/linux-2.6:
drm/i915: Initialise g4x watermarks for disabled pipes
drm/i915: Sanitize the output registers after resume
drm/i915/tv: Fix modeset flickering introduced in 7f58aabc3
drm/i915/tv: Only poll for TV connections
drm/i915/tv: Remember the detected TV type