| 5f293474c4c6c4dc2baaf2dfd486748b5986de76 |
|
23-Mar-2012 |
Andy Lutomirski <luto@mit.edu> |
x86-64: Inline vdso clock_gettime helpers
This is about a 3% speedup on Sandy Bridge.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: John Stultz <john.stultz@linaro.org>
|
| 91ec87d57fc38c529034e853687dfb7756de5406 |
|
23-Mar-2012 |
Andy Lutomirski <luto@mit.edu> |
x86-64: Simplify and optimize vdso clock_gettime monotonic variants
We used to store the wall-to-monotonic offset and the realtime base.
It's faster to precompute the monotonic base.
This is about a 3% speedup on Sandy Bridge for CLOCK_MONOTONIC.
It's much more impressive for CLOCK_MONOTONIC_COARSE.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: John Stultz <john.stultz@linaro.org>
|
| 2ab516575f2f273b19d95140d02c54612201e80a |
|
28-Feb-2012 |
Thomas Gleixner <tglx@linutronix.de> |
x86: vdso: Use seqcount instead of seqlock
The update of the vdso data happens under xtime_lock, so adding a
nested lock is pointless. Just use a seqcount to sync the readers.
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
|
| a939e817aa7e199d2fff05a67cb745be32dd5c2d |
|
02-Mar-2012 |
John Stultz <john.stultz@linaro.org> |
time: x86: Fix race switching from vsyscall to non-vsyscall clock
When switching from a vsyscall capable to a non-vsyscall capable
clocksource, there was a small race, where the last vsyscall
gettimeofday before the switch might return a invalid time value
using the new non-vsyscall enabled clocksource values after the
switch is complete.
This is due to the vsyscall code checking the vclock_mode once
outside of the seqcount protected section. After it reads the
vclock mode, it doesn't re-check that the sampled clock data
that is obtained in the seqcount critical section still matches.
The fix is to sample vclock_mode inside the protected section,
and as long as it isn't VCLOCK_NONE, return the calculated
value. If it has changed and is now VCLOCK_NONE, fall back
to the syscall gettime calculation.
v2:
* Cleanup checks as suggested by tglx
* Also fix same issue present in gettimeofday path
CC: Andy Lutomirski <luto@amacapital.net>
CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
|
| 8c400f6ce068366bc3517f1036bb99169cfec9cd |
|
18-Jul-2011 |
Borislav Petkov <bp@alien8.de> |
x86, vdso: Drop now wrong comment
Now that 1b3f2a72bbcfdf92e368a44448c45eb639b05b5e is in, it is very
important that the below lying comment be removed! :-)
Signed-off-by: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/20110718191054.GA18359@liondog.tnic
Acked-by: Andy Lutomirski <luto@mit.edu>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
|
| 98d0ac38ca7b1b7a552c9a2359174ff84decb600 |
|
14-Jul-2011 |
Andy Lutomirski <luto@mit.edu> |
x86-64: Move vread_tsc and vread_hpet into the vDSO
The vsyscall page now consists entirely of trap instructions.
Cc: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/637648f303f2ef93af93bae25186e9a1bea093f5.1310639973.git.luto@mit.edu
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
|
| 0d7b8547fb67d5c2a7d954c56b3715b0e708be4a |
|
05-Jun-2011 |
Andy Lutomirski <luto@MIT.EDU> |
x86-64: Remove kernel.vsyscall64 sysctl
It's unnecessary overhead in code that's supposed to be highly
optimized. Removing it allows us to remove one of the two
syscall instructions in the vsyscall page.
The only sensible use for it is for UML users, and it doesn't
fully address inconsistent vsyscall results on UML. The real
fix for UML is to stop using vsyscalls entirely.
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Jesper Juhl <jj@chaosbits.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: richard -rw- weinberger <richard.weinberger@gmail.com>
Cc: Mikael Pettersson <mikpe@it.uu.se>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Louis Rilling <Louis.Rilling@kerlabs.com>
Cc: Valdis.Kletnieks@vt.edu
Cc: pageexec@freemail.hu
Link: http://lkml.kernel.org/r/973ae803fe76f712da4b2740e66dccf452d3b1e4.1307292171.git.luto@mit.edu
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
| e9d35946c84c44e33e007123d3d595ccbd21d1a4 |
|
26-May-2011 |
Thomas Gleixner <tglx@linutronix.de> |
x86: vdso: Remove unused variable
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@mit.edu>
|
| 973aa8181e10050809b56ecbaadd01495766a19e |
|
23-May-2011 |
Andy Lutomirski <luto@MIT.EDU> |
x86-64: Optimize vDSO time()
This function just reads a 64-bit variable that's updated
atomically, so we don't need any locks.
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3C40e2700f8cda4d511e5910be1e633025d28b36c2.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
| f144a6b4d1688675d88990e29567b2335b48205e |
|
23-May-2011 |
Andy Lutomirski <luto@MIT.EDU> |
x86-64: Add time to vDSO
The only fast implementation of time(2) we expose is through the
vsyscall page and we want to get userspace to stop using the
vsyscall page. So make it available through the vDSO as well.
This is essentially a cut-n-paste job.
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3Cbf963bac5207de4b29613f27c42705e4371812a8.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
| 0f51f2852ccf0fe38a02d340d0ba625e8e32a863 |
|
23-May-2011 |
Andy Lutomirski <luto@MIT.EDU> |
x86-64: Vclock_gettime(CLOCK_MONOTONIC) can't ever see nsec < 0
vclock_gettime's do_monotonic helper can't ever generate a negative
nsec value, so it doesn't need to check whether it's negative. In
the CLOCK_MONOTONIC_COARSE case, ns can't ever exceed 2e9-1, so we
can avoid the loop entirely. This saves a single easily-predicted
branch.
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3Cd6d528d32c7a21618057cfc9005942a0fe5cb54a.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
| 8c49d9a74bac5ea3f18480307057241b808fcc0c |
|
23-May-2011 |
Andy Lutomirski <luto@MIT.EDU> |
x86-64: Clean up vdso/kernel shared variables
Variables that are shared between the vdso and the kernel are
currently a bit of a mess. They are each defined with their own
magic, they are accessed differently in the kernel, the vsyscall page,
and the vdso, and one of them (vsyscall_clock) doesn't even really
exist.
This changes them all to use a common mechanism. All of them are
delcared in vvar.h with a fixed address (validated by the linker
script). In the kernel (as before), they look like ordinary
read-write variables. In the vsyscall page and the vdso, they are
accessed through a new macro VVAR, which gives read-only access.
The vdso is now loaded verbatim into memory without any fixups. As a
side bonus, access from the vdso is faster because a level of
indirection is removed.
While we're at it, pack jiffies and vgetcpu_mode into the same
cacheline.
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3C7357882fbb51fa30491636a7b6528747301b7ee9.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
| da15cfdae03351c689736f8d142618592e3cebc3 |
|
20-Aug-2009 |
john stultz <johnstul@us.ibm.com> |
time: Introduce CLOCK_REALTIME_COARSE
After talking with some application writers who want very fast, but not
fine-grained timestamps, I decided to try to implement new clock_ids
to clock_gettime(): CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE
which returns the time at the last tick. This is very fast as we don't
have to access any hardware (which can be very painful if you're using
something like the acpi_pm clocksource), and we can even use the vdso
clock_gettime() method to avoid the syscall. The only trade off is you
only get low-res tick grained time resolution.
This isn't a new idea, I know Ingo has a patch in the -rt tree that made
the vsyscall gettimeofday() return coarse grained time when the
vsyscall64 sysctrl was set to 2. However this affects all applications
on a system.
With this method, applications can choose the proper speed/granularity
trade-off for themselves.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: nikolag@ca.ibm.com
Cc: Darren Hart <dvhltc@us.ibm.com>
Cc: arjan@infradead.org
Cc: jonathan@jonmasters.org
LKML-Reference: <1250734414.6897.5.camel@localhost.localdomain>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
| 2f65dd475c6a8a997145ea83cc3d2d5e6dc55af1 |
|
29-Apr-2009 |
John Wright <john.wright@hp.com> |
x86: gettimeofday() vDSO: fix segfault when tv == NULL
According to the gettimeofday(2) manual:
If either tv or tz is NULL, the corresponding structure is not
set or returned.
Since it is legal to give NULL as the tv argument, the code should make
sure tv is not NULL before trying to dereference it.
This issue manifests itself on x86_64 when vdso=0 is not on the kernel
command-line and libc uses the vDSO for gettimeofday() (e.g. glibc >=
2.7). A simple reproducer:
#include <stdio.h>
#include <sys/time.h>
int main(void)
{
struct timezone tz;
gettimeofday(NULL, &tz);
return 0;
}
See http://bugs.debian.org/466491 for more details.
[ Impact: fix gettimeofday(NULL, &tz) segfault ]
Signed-off-by: John Wright <john.wright@hp.com>
Cc: Andi Kleen <ak@suse.de>
Cc: John Wright <john.wright@hp.com>
LKML-Reference: <1241037121-14805-1-git-send-email-john.wright@hp.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
| 2ed84eeb8808cf3c9f039213ca137ffd7d753f0e |
|
12-Nov-2008 |
Steven Rostedt <srostedt@redhat.com> |
trace: rename unlikely profiler to branch profiler
Impact: name change of unlikely tracer and profiler
Ingo Molnar suggested changing the config from UNLIKELY_PROFILE
to BRANCH_PROFILING. I never did like the "unlikely" name so I
went one step farther, and renamed all the unlikely configurations
to a "BRANCH" variant.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
| 2b7d0390a6d6d595f43ea3806639664afe5b9ebe |
|
12-Nov-2008 |
Ingo Molnar <mingo@elte.hu> |
tracing: branch tracer, fix vdso crash
Impact: fix bootup crash
the branch tracer missed arch/x86/vdso/vclock_gettime.c from
disabling tracing, which caused such bootup crashes:
[ 201.840097] init[1]: segfault at 7fffed3fe7c0 ip 00007fffed3fea2e sp 000077
also clean up the ugly ifdefs in arch/x86/kernel/vsyscall_64.c by
creating DISABLE_UNLIKELY_PROFILE facility for code to turn off
instrumentation on a per file basis.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|
| 23adec554a7648f99c8acc0caf49c66320cd2b84 |
|
12-May-2008 |
Steven Rostedt <srostedt@redhat.com> |
x86: add notrace annotations to vsyscall.
Add the notrace annotations to the vsyscall functions - there we are
not in kernel context yet, so the tracer function cannot (and must not)
be called.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
| a1289643adb6272c04db9399653ae195072c482a |
|
15-May-2008 |
Andi Kleen <andi@firstfloor.org> |
x86: use explicit copy in vdso_gettimeofday()
Jeremy's gcc 3.4 seems to be unable to inline a 8 byte memcpy. But the
vdso doesn't support external references. Copy the structure members
of struct timezone explicitely instead.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
| 201c19948b879ed95ac986bc994af29d7cf4859f |
|
30-Jan-2008 |
Lucas Woods <woodzy@gmail.com> |
x86: remove duplicate includes
Signed-off-by: Lucas Woods <woodzy@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
| 7648b1330c335601b7c09c25f77a03cda128fcab |
|
11-Oct-2007 |
Thomas Gleixner <tglx@linutronix.de> |
x86_64: move vdso
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
|