From: Michael Ellerman <mpe@ellerman•id.au>
To: Christophe LEROY <christophe.leroy@c-s•fr>,
Anton Blanchard <anton@samba•org>
Cc: linuxppc-dev@lists•ozlabs.org, paulus@samba•org,
benh@kernel•crashing.org
Subject: Re: [PATCH] powerpc: Avoid taking a data miss on every userspace instruction miss
Date: Thu, 13 Apr 2017 20:22:40 +1000 [thread overview]
Message-ID: <8737dca9ov.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <09625197-3387-eeb6-5f80-5d14d1332b2d@c-s.fr>
Christophe LEROY <christophe.leroy@c-s•fr> writes:
> Hi Anton,
>
> Le 04/04/2017 =C3=A0 00:00, Anton Blanchard a =C3=A9crit :
>> Hi Christophe,
>>
>>>> - if (user_mode(regs))
>>>> + if (!is_exec && user_mode(regs))
>>>
>>> Shouldn't it also check 'is_write' ?
>>> If it is a store, is_write should be set, shouldn't it ?
>>
>> Thanks, Ben had the same suggestion. I'll add that further optimisation
>> in a subsequent patch.
>>
>
> For your information, I made some benchmark test using 'perf stat' with=20
> your app on MPC8321 and MPC885, and I got the following results:
MPC8321:
before 47386 faults=20
after 35181 faults -12205
is_write 35181 faults -12205=20
So that's good.
MPC885:
before: 176067 dTLB-load-misses=20
52722 iTLB-load-misses=20
25718 faults=20
after: 152462 dTLB-load-misses -23605
52715 iTLB-load-misses -7
19611 faults -6107
is_write: 147162 dTLB-load-misses -28905
52716 iTLB-load-misses -6
19610 faults -6108
Also good, and shows that is_write idea would be even better.
cheers
next prev parent reply other threads:[~2017-04-13 10:22 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-03 6:41 [PATCH] powerpc: Avoid taking a data miss on every userspace instruction miss Anton Blanchard
2017-04-03 18:55 ` LEROY Christophe
2017-04-03 22:00 ` Anton Blanchard
2017-04-12 16:15 ` Christophe LEROY
2017-04-13 10:22 ` Michael Ellerman [this message]
2017-04-06 13:06 ` Michael Ellerman
2017-04-13 1:16 ` Balbir Singh
2017-04-13 1:29 ` Anton Blanchard
2017-04-13 10:24 ` Michael Ellerman
-- strict thread matches above, loose matches on Subject: below --
2017-03-31 3:05 [PATCH] " Anton Blanchard
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