From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, Nick Piggin <nickpiggin@yahoo.com.au>,
Jens Axboe <jens.axboe@oracle.com>
Subject: Re: [PATCH 0 of 9] x86/smp function calls: convert x86 tlb flushes to use function calls [POST 2]
Date: Tue, 19 Aug 2008 00:44:04 -0700 [thread overview]
Message-ID: <48AA79C4.8060309@goop.org> (raw)
In-Reply-To: <20080819073214.GD9807@one.firstfloor.org>
Andi Kleen wrote:
>> nice stuff!
>>
>
> If only those 35% wouldn't be there ...
>
Don't pay attention to that number. It's only the extra latency of a HT
context->HT context function call + tlb flush. Which means 1) the tlb
is shared anyway, so the extra flush is redundant, 2) they're not really
concurrent, 3) it's going down the single-cpu call, rather than the
multi-cpu one, 4) it's only measuring the latency for a particular tlb
flush, and doesn't take into account any throughput improvements the
extra queueing may add.
I don't really know what the nett consequence of all that is, but it
means the number has almost no bearing on multicore results, esp with >2
cores.
J
next prev parent reply other threads:[~2008-08-19 7:44 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-18 18:23 [PATCH 0 of 9] x86/smp function calls: convert x86 tlb flushes to use function calls [POST 2] Jeremy Fitzhardinge
2008-08-18 18:23 ` [PATCH 1 of 9] x86: put tlb_flush_others() stats in debugfs Jeremy Fitzhardinge
2008-08-18 18:23 ` [PATCH 2 of 9] x86-32: use smp_call_function_mask for SMP TLB invalidations Jeremy Fitzhardinge
2008-08-18 18:23 ` [PATCH 3 of 9] x86-64: " Jeremy Fitzhardinge
2008-08-18 18:23 ` [PATCH 4 of 9] x86: make tlb_32|64 closer Jeremy Fitzhardinge
2008-08-18 18:23 ` [PATCH 5 of 9] x86: unify tlb.c Jeremy Fitzhardinge
2008-08-18 18:23 ` [PATCH 6 of 9] smp_function_call: add multiple queues for scalability Jeremy Fitzhardinge
2008-08-18 18:23 ` [PATCH 7 of 9] x86: add multiple smp_call_function queues Jeremy Fitzhardinge
2008-08-18 18:23 ` [PATCH 8 of 9] x86: make number of smp_call_function queues truely configurable Jeremy Fitzhardinge
2008-08-18 18:23 ` [PATCH 9 of 9] smp function calls: add kernel parameter to disable multiple queues Jeremy Fitzhardinge
2008-08-19 0:45 ` [PATCH 0 of 9] x86/smp function calls: convert x86 tlb flushes to use function calls [POST 2] Ingo Molnar
2008-08-19 1:28 ` Ingo Molnar
2008-08-19 6:18 ` Jeremy Fitzhardinge
2008-08-19 9:27 ` Ingo Molnar
2008-08-19 14:58 ` Jeremy Fitzhardinge
2008-08-19 9:45 ` Peter Zijlstra
2008-08-19 14:58 ` Jeremy Fitzhardinge
2008-08-19 5:37 ` Jeremy Fitzhardinge
2008-08-19 9:31 ` Ingo Molnar
2008-08-19 9:56 ` Nick Piggin
2008-08-19 10:20 ` Ingo Molnar
2008-08-19 11:08 ` Nick Piggin
2008-08-19 11:44 ` Ingo Molnar
2008-08-19 10:24 ` Ingo Molnar
2008-08-19 10:49 ` Nick Piggin
2008-08-19 10:31 ` Andi Kleen
2008-08-19 11:04 ` Nick Piggin
2008-08-19 11:20 ` Andi Kleen
2008-08-19 7:32 ` Andi Kleen
2008-08-19 7:44 ` Jeremy Fitzhardinge [this message]
2008-08-19 7:48 ` Andi Kleen
2008-08-19 8:04 ` Jeremy Fitzhardinge
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