From: Nick Piggin <npiggin@gmail.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Nick Piggin <npiggin@kernel.dk>, Andi Kleen <ak@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 3/3] brlocks/lglocks: turn into functions
Date: Wed, 9 May 2012 17:35:53 +1000 [thread overview]
Message-ID: <CAPa8GCCSBxZZVS+ROshEW9qXwXLpwkoeiFiL0xnSGW6rsDQyrA@mail.gmail.com> (raw)
In-Reply-To: <87sjfcfynb.fsf@rustcorp.com.au>
On 7 May 2012 13:39, Rusty Russell <rusty@rustcorp.com.au> wrote:
> On Fri, 20 Apr 2012 21:21:49 +1000, Nick Piggin <npiggin@kernel.dk> wrote:
>> This still not merged?
>
> No, I've been away. I've put it in -next for tomorrow, though I'm not
> sure what the best way to get it to Linus next merge window.
>
>> There is a reason, which is performance. Extra function call, but also
>> IIRC the percpu accessor was not so fast doing it this way. Maybe
>> that's improved...
>>
>> So what's the performance difference?
>
> What benchmarks you usually run? Feel free to try it out and report
> back; I only have small hardware here.
Nothing big. The actual scalability should be unchanged, because you're
not going to be dirtying any shared cachelines. It's the use of dynamic
percpu allocator and out of line calls etc which will slow down straight
line performance.
How many microseconds does it take to stat("./dir1/dir2/myfile"), for
example?
`git diff` of a large tree, for something more realistic but still going to
exercise that path.
WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <npiggin@gmail.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Nick Piggin <npiggin@kernel.dk>, Andi Kleen <ak@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 3/3] brlocks/lglocks: turn into functions
Date: Wed, 9 May 2012 17:35:53 +1000 [thread overview]
Message-ID: <CAPa8GCCSBxZZVS+ROshEW9qXwXLpwkoeiFiL0xnSGW6rsDQyrA@mail.gmail.com> (raw)
In-Reply-To: <87sjfcfynb.fsf@rustcorp.com.au>
On 7 May 2012 13:39, Rusty Russell <rusty@rustcorp.com.au> wrote:
> On Fri, 20 Apr 2012 21:21:49 +1000, Nick Piggin <npiggin@kernel.dk> wrote:
>> This still not merged?
>
> No, I've been away. I've put it in -next for tomorrow, though I'm not
> sure what the best way to get it to Linus next merge window.
>
>> There is a reason, which is performance. Extra function call, but also
>> IIRC the percpu accessor was not so fast doing it this way. Maybe
>> that's improved...
>>
>> So what's the performance difference?
>
> What benchmarks you usually run? Feel free to try it out and report
> back; I only have small hardware here.
Nothing big. The actual scalability should be unchanged, because you're
not going to be dirtying any shared cachelines. It's the use of dynamic
percpu allocator and out of line calls etc which will slow down straight
line performance.
How many microseconds does it take to stat("./dir1/dir2/myfile"), for
example?
`git diff` of a large tree, for something more realistic but still going to
exercise that path.
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next prev parent reply other threads:[~2012-05-09 7:35 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-27 23:22 [PATCH] cpumask: fix lg_lock/br_lock Rusty Russell
2012-02-27 23:53 ` Andrew Morton
2012-02-27 23:53 ` Andrew Morton
2012-02-28 8:43 ` Ingo Molnar
2012-02-28 11:25 ` Andi Kleen
2012-02-28 12:51 ` Ingo Molnar
2012-02-28 21:27 ` Andrew Morton
2012-02-29 5:44 ` Srivatsa S. Bhat
2012-02-29 9:17 ` Ingo Molnar
2012-02-29 11:12 ` Srivatsa S. Bhat
2012-03-01 7:38 ` Ingo Molnar
2012-03-01 9:15 ` Srivatsa S. Bhat
2012-03-01 9:45 ` Ingo Molnar
2012-03-01 9:56 ` Srivatsa S. Bhat
2012-03-01 8:12 ` Srivatsa S. Bhat
2012-03-01 8:24 ` Srivatsa S. Bhat
2012-03-01 8:12 ` Srivatsa S. Bhat
2012-03-01 8:15 ` [PATCH 1/3] CPU hotplug: Fix issues with callback registration Srivatsa S. Bhat
2012-03-01 8:27 ` Srivatsa S. Bhat
2012-03-01 8:15 ` Srivatsa S. Bhat
2012-03-01 8:16 ` [PATCH 2/3] CPU hotplug, arch/powerpc: Fix CPU hotplug " Srivatsa S. Bhat
2012-03-01 8:28 ` Srivatsa S. Bhat
2012-03-01 8:16 ` Srivatsa S. Bhat
2012-03-01 8:18 ` [PATCH 3/3] CPU hotplug, arch/sparc: " Srivatsa S. Bhat
2012-03-01 8:30 ` Srivatsa S. Bhat
2012-03-01 8:18 ` Srivatsa S. Bhat
2012-02-29 8:29 ` [PATCH] cpumask: fix lg_lock/br_lock Ingo Molnar
2012-02-29 8:58 ` Peter Zijlstra
2012-02-29 9:32 ` Ingo Molnar
2012-02-28 11:24 ` Andi Kleen
2012-03-05 7:02 ` Rusty Russell
2012-03-05 7:03 ` [PATCH 1/3] lglock: remove online variants of lock Rusty Russell
2012-04-20 11:12 ` Nick Piggin
2012-03-05 7:04 ` [PATCH 2/3] brlocks/lglocks: API cleanups Rusty Russell
2012-03-05 7:05 ` [PATCH 3/3] brlocks/lglocks: turn into functions Rusty Russell
2012-04-20 11:21 ` Nick Piggin
2012-05-07 3:39 ` Rusty Russell
2012-05-07 5:46 ` Al Viro
2012-05-08 3:59 ` [PATCH 1/3] lglock: remove online variants of lock Rusty Russell
2012-05-08 4:50 ` Al Viro
2012-05-08 6:12 ` Rusty Russell
2012-05-08 4:02 ` [PATCH 2/3] brlocks/lglocks: API cleanups Rusty Russell
2012-05-08 4:02 ` [PATCH 3/3] brlocks/lglocks: turn into functions Rusty Russell
2012-05-09 7:35 ` Nick Piggin [this message]
2012-05-09 7:35 ` Nick Piggin
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