On Tue, Jun 23, 2015 at 07:50:12PM +0200, Peter Zijlstra wrote:
> On Tue, Jun 23, 2015 at 04:56:39PM +0200, Daniel Wagner wrote:
> > flock02
> > mean variance sigma max
> > min
> > tip-1 11.8994 0.5874 0.7664 13.2022
> > 8.6324
> > tip-2 11.7394 0.5252 0.7247 13.2540
> > 9.7513
> > tip-3 11.8155 0.5288 0.7272 13.2700
> > 9.9480
> > tip+percpu-rswem-1 15.3601 0.8981 0.9477 16.8116
> > 12.6910
> > tip+percpu-rswem-2 15.2558 0.8442 0.9188 17.0199
> > 12.9586
> > tip+percpu-rswem-3 15.5297 0.6386 0.7991 17.4392
> > 12.7992
>
> I did indeed manage to get flock02 down to a usable level and found:
Aside from the flock_lock_file function moving up, we also get an
increase in _raw_spin_lock.
Before:
5.17% 5.17% flock02 [kernel.vmlinux] [k]
_raw_spin_lock
|
---_raw_spin_lock
|
|--99.75%-- flock_lock_file_wait
| sys_flock
| entry_SYSCALL_64_fastpath
| flock
--0.25%-- [...]
After:
7.20% 7.20% flock02 [kernel.vmlinux] [k]
_raw_spin_lock
|
---_raw_spin_lock
|
|--52.23%-- flock_lock_file_wait
| sys_flock
| entry_SYSCALL_64_fastpath
| flock
|
|--25.92%-- flock_lock_file
| flock_lock_file_wait
| sys_flock
| entry_SYSCALL_64_fastpath
| flock
|
|--21.42%-- locks_delete_lock_ctx
| flock_lock_file
| flock_lock_file_wait
| sys_flock
| entry_SYSCALL_64_fastpath
| flock
--0.43%-- [...]
And its not at all clear to me why this would be. It looks like
FILE_LOCK_DEFERRED is happening, but I've not yet figured out why that
would be.
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