LinuxLists.cc - [bug-report] possible performance problem in ret_to_user_from

2022-12-26 09:09:57

Subject: [bug-report] possible performance problem in ret_to_user_from_irq

hi folks.

I found a performance problem which is introduced by commit
32d59773da38 ("arm: add support for TIF_NOTIFY_SIGNAL").
After the commit, any bit in the range of 0..15 will cause
do_work_pending() to be invoked. More frequent do_work_pending()
invoked possible result in worse performance.

Some of the tests I've done， as follows:
lmbench test base with patch
./lat_ctx -P 1 -s 0 2 7.3167 11.04
./lat_ctx -P 1 -s 16 2 8.0467 14.5367
./lat_ctx -P 1 -s 64 2 7.8667 11.43
./lat_ctx -P 1 -s 16 16 16.47 18.3667
./lat_pipe -P 1 28.1671 44.7904

libMicro-0.4.1 test base with patch
./cascade_cond -E -C 200\
-L -S -W -N "c_cond_1" -I 100 286.3333 358

When I adjust test bit, the performance problem gone.
- movs r1, r1, lsl #16
+ ldr r2, =#_TIF_WORK_MASK
+ tst r1, r2

Does anyone have a good suggestion for this problem?
should just test _TIF_WORK_MASK, as before?

2023-01-03 10:43:05

by Russell King (Oracle)

[permalink] [raw]

Subject: Re: [bug-report] possible performance problem in ret_to_user_from_irq

On Mon, Dec 26, 2022 at 04:45:20PM +0800, Hui Tang wrote:
> hi folks.
>
> I found a performance problem which is introduced by commit
> 32d59773da38 ("arm: add support for TIF_NOTIFY_SIGNAL").
> After the commit, any bit in the range of 0..15 will cause
> do_work_pending() to be invoked. More frequent do_work_pending()
> invoked possible result in worse performance.
>
> Some of the tests I've done， as follows:
> lmbench test base with patch
> ./lat_ctx -P 1 -s 0 2 7.3167 11.04
> ./lat_ctx -P 1 -s 16 2 8.0467 14.5367
> ./lat_ctx -P 1 -s 64 2 7.8667 11.43
> ./lat_ctx -P 1 -s 16 16 16.47 18.3667
> ./lat_pipe -P 1 28.1671 44.7904
>
> libMicro-0.4.1 test base with patch
> ./cascade_cond -E -C 200\
> -L -S -W -N "c_cond_1" -I 100 286.3333 358
>
> When I adjust test bit, the performance problem gone.
> - movs r1, r1, lsl #16
> + ldr r2, =#_TIF_WORK_MASK
> + tst r1, r2
>
> Does anyone have a good suggestion for this problem?
> should just test _TIF_WORK_MASK, as before?

I think it should be fine - but I would suggest re-organising the
TIF definitions so that those TIF bits that shouldn't trigger
do_work_pending are not in the first 16 bits.

Note that all four bits in _TIF_SYSCALL_WORK need to stay within
an 8-bit even-bit-aligned range, so the value is suitable for an
immediate assembly constant.

I'd suggest moving the TIF definitions for 20 to 19, and 4..7 to
20..23, and then 8 to 4.

Thanks.

--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

2023-01-03 14:38:42

by Jens Axboe

[permalink] [raw]

Subject: Re: [bug-report] possible performance problem in ret_to_user_from_irq

On 1/3/23 3:06?AM, Russell King (Oracle) wrote:
> On Mon, Dec 26, 2022 at 04:45:20PM +0800, Hui Tang wrote:
>> hi folks.
>>
>> I found a performance problem which is introduced by commit
>> 32d59773da38 ("arm: add support for TIF_NOTIFY_SIGNAL").
>> After the commit, any bit in the range of 0..15 will cause
>> do_work_pending() to be invoked. More frequent do_work_pending()
>> invoked possible result in worse performance.
>>
>> Some of the tests I've done? as follows:
>> lmbench test base with patch
>> ./lat_ctx -P 1 -s 0 2 7.3167 11.04
>> ./lat_ctx -P 1 -s 16 2 8.0467 14.5367
>> ./lat_ctx -P 1 -s 64 2 7.8667 11.43
>> ./lat_ctx -P 1 -s 16 16 16.47 18.3667
>> ./lat_pipe -P 1 28.1671 44.7904
>>
>> libMicro-0.4.1 test base with patch
>> ./cascade_cond -E -C 200\
>> -L -S -W -N "c_cond_1" -I 100 286.3333 358
>>
>> When I adjust test bit, the performance problem gone.
>> - movs r1, r1, lsl #16
>> + ldr r2, =#_TIF_WORK_MASK
>> + tst r1, r2
>>
>> Does anyone have a good suggestion for this problem?
>> should just test _TIF_WORK_MASK, as before?
>
> I think it should be fine - but I would suggest re-organising the
> TIF definitions so that those TIF bits that shouldn't trigger
> do_work_pending are not in the first 16 bits.
>
> Note that all four bits in _TIF_SYSCALL_WORK need to stay within
> an 8-bit even-bit-aligned range, so the value is suitable for an
> immediate assembly constant.
>
> I'd suggest moving the TIF definitions for 20 to 19, and 4..7 to
> 20..23, and then 8 to 4.

Like this?

diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index aecc403b2880..7f092cb55a41 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -128,15 +128,16 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
#define TIF_NEED_RESCHED 1 /* rescheduling necessary */
#define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
#define TIF_UPROBE 3 /* breakpointed or singlestepping */
-#define TIF_SYSCALL_TRACE 4 /* syscall trace active */
-#define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
-#define TIF_SYSCALL_TRACEPOINT 6 /* syscall tracepoint instrumentation */
-#define TIF_SECCOMP 7 /* seccomp syscall filtering active */
-#define TIF_NOTIFY_SIGNAL 8 /* signal notifications exist */
+#define TIF_NOTIFY_SIGNAL 4 /* signal notifications exist */

#define TIF_USING_IWMMXT 17
#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
-#define TIF_RESTORE_SIGMASK 20
+#define TIF_RESTORE_SIGMASK 19
+#define TIF_SYSCALL_TRACE 20 /* syscall trace active */
+#define TIF_SYSCALL_AUDIT 21 /* syscall auditing active */
+#define TIF_SYSCALL_TRACEPOINT 22 /* syscall tracepoint instrumentation */
+#define TIF_SECCOMP 23 /* seccomp syscall filtering active */
+

#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)

--
Jens Axboe

2023-01-03 14:56:24

by Russell King (Oracle)

[permalink] [raw]

Subject: Re: [bug-report] possible performance problem in ret_to_user_from_irq

On Tue, Jan 03, 2023 at 07:25:26AM -0700, Jens Axboe wrote:
> On 1/3/23 3:06?AM, Russell King (Oracle) wrote:
> > On Mon, Dec 26, 2022 at 04:45:20PM +0800, Hui Tang wrote:
> >> hi folks.
> >>
> >> I found a performance problem which is introduced by commit
> >> 32d59773da38 ("arm: add support for TIF_NOTIFY_SIGNAL").
> >> After the commit, any bit in the range of 0..15 will cause
> >> do_work_pending() to be invoked. More frequent do_work_pending()
> >> invoked possible result in worse performance.
> >>
> >> Some of the tests I've done? as follows:
> >> lmbench test base with patch
> >> ./lat_ctx -P 1 -s 0 2 7.3167 11.04
> >> ./lat_ctx -P 1 -s 16 2 8.0467 14.5367
> >> ./lat_ctx -P 1 -s 64 2 7.8667 11.43
> >> ./lat_ctx -P 1 -s 16 16 16.47 18.3667
> >> ./lat_pipe -P 1 28.1671 44.7904
> >>
> >> libMicro-0.4.1 test base with patch
> >> ./cascade_cond -E -C 200\
> >> -L -S -W -N "c_cond_1" -I 100 286.3333 358
> >>
> >> When I adjust test bit, the performance problem gone.
> >> - movs r1, r1, lsl #16
> >> + ldr r2, =#_TIF_WORK_MASK
> >> + tst r1, r2
> >>
> >> Does anyone have a good suggestion for this problem?
> >> should just test _TIF_WORK_MASK, as before?
> >
> > I think it should be fine - but I would suggest re-organising the
> > TIF definitions so that those TIF bits that shouldn't trigger
> > do_work_pending are not in the first 16 bits.
> >
> > Note that all four bits in _TIF_SYSCALL_WORK need to stay within
> > an 8-bit even-bit-aligned range, so the value is suitable for an
> > immediate assembly constant.
> >
> > I'd suggest moving the TIF definitions for 20 to 19, and 4..7 to
> > 20..23, and then 8 to 4.
>
> Like this?
>
> diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
> index aecc403b2880..7f092cb55a41 100644
> --- a/arch/arm/include/asm/thread_info.h
> +++ b/arch/arm/include/asm/thread_info.h
> @@ -128,15 +128,16 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
> #define TIF_NEED_RESCHED 1 /* rescheduling necessary */
> #define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
> #define TIF_UPROBE 3 /* breakpointed or singlestepping */
> -#define TIF_SYSCALL_TRACE 4 /* syscall trace active */
> -#define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
> -#define TIF_SYSCALL_TRACEPOINT 6 /* syscall tracepoint instrumentation */
> -#define TIF_SECCOMP 7 /* seccomp syscall filtering active */
> -#define TIF_NOTIFY_SIGNAL 8 /* signal notifications exist */
> +#define TIF_NOTIFY_SIGNAL 4 /* signal notifications exist */
>
> #define TIF_USING_IWMMXT 17
> #define TIF_MEMDIE 18 /* is terminating due to OOM killer */
> -#define TIF_RESTORE_SIGMASK 20
> +#define TIF_RESTORE_SIGMASK 19
> +#define TIF_SYSCALL_TRACE 20 /* syscall trace active */
> +#define TIF_SYSCALL_AUDIT 21 /* syscall auditing active */
> +#define TIF_SYSCALL_TRACEPOINT 22 /* syscall tracepoint instrumentation */
> +#define TIF_SECCOMP 23 /* seccomp syscall filtering active */
> +
>
> #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
> #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)

Yep, LGTM, thanks.

--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

2023-01-03 15:24:31

by Jens Axboe

[permalink] [raw]

Subject: Re: [bug-report] possible performance problem in ret_to_user_from_irq

On 1/3/23 7:34?AM, Russell King (Oracle) wrote:
> On Tue, Jan 03, 2023 at 07:25:26AM -0700, Jens Axboe wrote:
>> On 1/3/23 3:06?AM, Russell King (Oracle) wrote:
>>> On Mon, Dec 26, 2022 at 04:45:20PM +0800, Hui Tang wrote:
>>>> hi folks.
>>>>
>>>> I found a performance problem which is introduced by commit
>>>> 32d59773da38 ("arm: add support for TIF_NOTIFY_SIGNAL").
>>>> After the commit, any bit in the range of 0..15 will cause
>>>> do_work_pending() to be invoked. More frequent do_work_pending()
>>>> invoked possible result in worse performance.
>>>>
>>>> Some of the tests I've done? as follows:
>>>> lmbench test base with patch
>>>> ./lat_ctx -P 1 -s 0 2 7.3167 11.04
>>>> ./lat_ctx -P 1 -s 16 2 8.0467 14.5367
>>>> ./lat_ctx -P 1 -s 64 2 7.8667 11.43
>>>> ./lat_ctx -P 1 -s 16 16 16.47 18.3667
>>>> ./lat_pipe -P 1 28.1671 44.7904
>>>>
>>>> libMicro-0.4.1 test base with patch
>>>> ./cascade_cond -E -C 200\
>>>> -L -S -W -N "c_cond_1" -I 100 286.3333 358
>>>>
>>>> When I adjust test bit, the performance problem gone.
>>>> - movs r1, r1, lsl #16
>>>> + ldr r2, =#_TIF_WORK_MASK
>>>> + tst r1, r2
>>>>
>>>> Does anyone have a good suggestion for this problem?
>>>> should just test _TIF_WORK_MASK, as before?
>>>
>>> I think it should be fine - but I would suggest re-organising the
>>> TIF definitions so that those TIF bits that shouldn't trigger
>>> do_work_pending are not in the first 16 bits.
>>>
>>> Note that all four bits in _TIF_SYSCALL_WORK need to stay within
>>> an 8-bit even-bit-aligned range, so the value is suitable for an
>>> immediate assembly constant.
>>>
>>> I'd suggest moving the TIF definitions for 20 to 19, and 4..7 to
>>> 20..23, and then 8 to 4.
>>
>> Like this?
>>
>> diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
>> index aecc403b2880..7f092cb55a41 100644
>> --- a/arch/arm/include/asm/thread_info.h
>> +++ b/arch/arm/include/asm/thread_info.h
>> @@ -128,15 +128,16 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
>> #define TIF_NEED_RESCHED 1 /* rescheduling necessary */
>> #define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
>> #define TIF_UPROBE 3 /* breakpointed or singlestepping */
>> -#define TIF_SYSCALL_TRACE 4 /* syscall trace active */
>> -#define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
>> -#define TIF_SYSCALL_TRACEPOINT 6 /* syscall tracepoint instrumentation */
>> -#define TIF_SECCOMP 7 /* seccomp syscall filtering active */
>> -#define TIF_NOTIFY_SIGNAL 8 /* signal notifications exist */
>> +#define TIF_NOTIFY_SIGNAL 4 /* signal notifications exist */
>>
>> #define TIF_USING_IWMMXT 17
>> #define TIF_MEMDIE 18 /* is terminating due to OOM killer */
>> -#define TIF_RESTORE_SIGMASK 20
>> +#define TIF_RESTORE_SIGMASK 19
>> +#define TIF_SYSCALL_TRACE 20 /* syscall trace active */
>> +#define TIF_SYSCALL_AUDIT 21 /* syscall auditing active */
>> +#define TIF_SYSCALL_TRACEPOINT 22 /* syscall tracepoint instrumentation */
>> +#define TIF_SECCOMP 23 /* seccomp syscall filtering active */
>> +
>>
>> #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
>> #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
>
> Yep, LGTM, thanks.

Hui Tang, can you give it a whirl? Just checked and it applies to
5.10-stable as well, just with a slight offset.

--
Jens Axboe

2023-01-04 01:45:20

by Hui Tang

[permalink] [raw]

Subject: Re: [bug-report] possible performance problem in ret_to_user_from_irq

On 2023/1/3 22:59, Jens Axboe wrote:
> On 1/3/23 7:34?AM, Russell King (Oracle) wrote:
>> On Tue, Jan 03, 2023 at 07:25:26AM -0700, Jens Axboe wrote:
>>> On 1/3/23 3:06?AM, Russell King (Oracle) wrote:
>>>> On Mon, Dec 26, 2022 at 04:45:20PM +0800, Hui Tang wrote:
>>>>> hi folks.
>>>>>
>>>>> I found a performance problem which is introduced by commit
>>>>> 32d59773da38 ("arm: add support for TIF_NOTIFY_SIGNAL").
>>>>> After the commit, any bit in the range of 0..15 will cause
>>>>> do_work_pending() to be invoked. More frequent do_work_pending()
>>>>> invoked possible result in worse performance.
>>>>>
>>>>> Some of the tests I've done? as follows:
>>>>> lmbench test base with patch
>>>>> ./lat_ctx -P 1 -s 0 2 7.3167 11.04
>>>>> ./lat_ctx -P 1 -s 16 2 8.0467 14.5367
>>>>> ./lat_ctx -P 1 -s 64 2 7.8667 11.43
>>>>> ./lat_ctx -P 1 -s 16 16 16.47 18.3667
>>>>> ./lat_pipe -P 1 28.1671 44.7904
>>>>>
>>>>> libMicro-0.4.1 test base with patch
>>>>> ./cascade_cond -E -C 200\
>>>>> -L -S -W -N "c_cond_1" -I 100 286.3333 358
>>>>>
>>>>> When I adjust test bit, the performance problem gone.
>>>>> - movs r1, r1, lsl #16
>>>>> + ldr r2, =#_TIF_WORK_MASK
>>>>> + tst r1, r2
>>>>>
>>>>> Does anyone have a good suggestion for this problem?
>>>>> should just test _TIF_WORK_MASK, as before?
>>>>
>>>> I think it should be fine - but I would suggest re-organising the
>>>> TIF definitions so that those TIF bits that shouldn't trigger
>>>> do_work_pending are not in the first 16 bits.
>>>>
>>>> Note that all four bits in _TIF_SYSCALL_WORK need to stay within
>>>> an 8-bit even-bit-aligned range, so the value is suitable for an
>>>> immediate assembly constant.
>>>>
>>>> I'd suggest moving the TIF definitions for 20 to 19, and 4..7 to
>>>> 20..23, and then 8 to 4.
>>>
>>> Like this?
>>>
>>> diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
>>> index aecc403b2880..7f092cb55a41 100644
>>> --- a/arch/arm/include/asm/thread_info.h
>>> +++ b/arch/arm/include/asm/thread_info.h
>>> @@ -128,15 +128,16 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
>>> #define TIF_NEED_RESCHED 1 /* rescheduling necessary */
>>> #define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
>>> #define TIF_UPROBE 3 /* breakpointed or singlestepping */
>>> -#define TIF_SYSCALL_TRACE 4 /* syscall trace active */
>>> -#define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
>>> -#define TIF_SYSCALL_TRACEPOINT 6 /* syscall tracepoint instrumentation */
>>> -#define TIF_SECCOMP 7 /* seccomp syscall filtering active */
>>> -#define TIF_NOTIFY_SIGNAL 8 /* signal notifications exist */
>>> +#define TIF_NOTIFY_SIGNAL 4 /* signal notifications exist */
>>>
>>> #define TIF_USING_IWMMXT 17
>>> #define TIF_MEMDIE 18 /* is terminating due to OOM killer */
>>> -#define TIF_RESTORE_SIGMASK 20
>>> +#define TIF_RESTORE_SIGMASK 19
>>> +#define TIF_SYSCALL_TRACE 20 /* syscall trace active */
>>> +#define TIF_SYSCALL_AUDIT 21 /* syscall auditing active */
>>> +#define TIF_SYSCALL_TRACEPOINT 22 /* syscall tracepoint instrumentation */
>>> +#define TIF_SECCOMP 23 /* seccomp syscall filtering active */
>>> +
>>>
>>> #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
>>> #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
>>
>> Yep, LGTM, thanks.
>
> Hui Tang, can you give it a whirl? Just checked and it applies to
> 5.10-stable as well, just with a slight offset.

Okay, I'll test it today.

2023-01-04 07:25:04

by Hui Tang

[permalink] [raw]

Subject: Re: [bug-report] possible performance problem in ret_to_user_from_irq

2023-01-04 15:06:54

by Jens Axboe

[permalink] [raw]

Subject: Re: [bug-report] possible performance problem in ret_to_user_from_irq

On 1/4/23 12:04?AM, Hui Tang wrote:
>
>
> On 2023/1/3 22:59, Jens Axboe wrote:
>> On 1/3/23 7:34?AM, Russell King (Oracle) wrote:
>>> On Tue, Jan 03, 2023 at 07:25:26AM -0700, Jens Axboe wrote:
>>>> On 1/3/23 3:06?AM, Russell King (Oracle) wrote:
>>>>> On Mon, Dec 26, 2022 at 04:45:20PM +0800, Hui Tang wrote:
>>>>>> hi folks.
>>>>>>
>>>>>> I found a performance problem which is introduced by commit
>>>>>> 32d59773da38 ("arm: add support for TIF_NOTIFY_SIGNAL").
>>>>>> After the commit, any bit in the range of 0..15 will cause
>>>>>> do_work_pending() to be invoked. More frequent do_work_pending()
>>>>>> invoked possible result in worse performance.
>>>>>>
>>>>>> Some of the tests I've done? as follows:
>>>>>> lmbench test base with patch
>>>>>> ./lat_ctx -P 1 -s 0 2 7.3167 11.04
>>>>>> ./lat_ctx -P 1 -s 16 2 8.0467 14.5367
>>>>>> ./lat_ctx -P 1 -s 64 2 7.8667 11.43
>>>>>> ./lat_ctx -P 1 -s 16 16 16.47 18.3667
>>>>>> ./lat_pipe -P 1 28.1671 44.7904
>>>>>>
>>>>>> libMicro-0.4.1 test base with patch
>>>>>> ./cascade_cond -E -C 200\
>>>>>> -L -S -W -N "c_cond_1" -I 100 286.3333 358
>>>>>>
>>>>>> When I adjust test bit, the performance problem gone.
>>>>>> - movs r1, r1, lsl #16
>>>>>> + ldr r2, =#_TIF_WORK_MASK
>>>>>> + tst r1, r2
>>>>>>
>>>>>> Does anyone have a good suggestion for this problem?
>>>>>> should just test _TIF_WORK_MASK, as before?
>>>>>
>>>>> I think it should be fine - but I would suggest re-organising the
>>>>> TIF definitions so that those TIF bits that shouldn't trigger
>>>>> do_work_pending are not in the first 16 bits.
>>>>>
>>>>> Note that all four bits in _TIF_SYSCALL_WORK need to stay within
>>>>> an 8-bit even-bit-aligned range, so the value is suitable for an
>>>>> immediate assembly constant.
>>>>>
>>>>> I'd suggest moving the TIF definitions for 20 to 19, and 4..7 to
>>>>> 20..23, and then 8 to 4.
>>>>
>>>> Like this?
>>>>
>>>> diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
>>>> index aecc403b2880..7f092cb55a41 100644
>>>> --- a/arch/arm/include/asm/thread_info.h
>>>> +++ b/arch/arm/include/asm/thread_info.h
>>>> @@ -128,15 +128,16 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
>>>> #define TIF_NEED_RESCHED 1 /* rescheduling necessary */
>>>> #define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
>>>> #define TIF_UPROBE 3 /* breakpointed or singlestepping */
>>>> -#define TIF_SYSCALL_TRACE 4 /* syscall trace active */
>>>> -#define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
>>>> -#define TIF_SYSCALL_TRACEPOINT 6 /* syscall tracepoint instrumentation */
>>>> -#define TIF_SECCOMP 7 /* seccomp syscall filtering active */
>>>> -#define TIF_NOTIFY_SIGNAL 8 /* signal notifications exist */
>>>> +#define TIF_NOTIFY_SIGNAL 4 /* signal notifications exist */
>>>>
>>>> #define TIF_USING_IWMMXT 17
>>>> #define TIF_MEMDIE 18 /* is terminating due to OOM killer */
>>>> -#define TIF_RESTORE_SIGMASK 20
>>>> +#define TIF_RESTORE_SIGMASK 19
>>>> +#define TIF_SYSCALL_TRACE 20 /* syscall trace active */
>>>> +#define TIF_SYSCALL_AUDIT 21 /* syscall auditing active */
>>>> +#define TIF_SYSCALL_TRACEPOINT 22 /* syscall tracepoint instrumentation */
>>>> +#define TIF_SECCOMP 23 /* seccomp syscall filtering active */
>>>> +
>>>>
>>>> #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
>>>> #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
>>>
>>> Yep, LGTM, thanks.
>>
>> Hui Tang, can you give it a whirl? Just checked and it applies to
>> 5.10-stable as well, just with a slight offset.
>
> With the latest patch, the testcase rusults shown in the 'new patch' column.
> I also retested previous commit of 32d59773da38, the results shown in the 'base' column.
>
> lmbench test base 32d59773da38 new patch
> ./lat_ctx -P 1 -s 0 2 8.04 11.04 8.25
> ./lat_ctx -P 1 -s 16 2 9.08 14.5367 9.26
> ./lat_ctx -P 1 -s 64 2 8.78 11.43 8.71
> ./lat_ctx -P 1 -s 16 16 17.22 18.3667 17.32
> ./lat_pipe -P 1 43.5021 44.7904 41.3729
>
> libMicro-0.4.1 test base 32d59773da38 new patch
> ./cascade_cond -E -C 200\
> -L -S -W -N "c_cond_1" -I 100 281 358 281
>
> The performance problem also seem to gone with the latest patch, thanks.

Thanks for testing! I'm going to send it out and add your tested-by (and
reported-by).

--
Jens Axboe