From: Rik van Riel <riel@redhat.com>
To: Mel Gorman <mgorman@suse.de>, Alex Shi <alex.shi@linaro.org>,
Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
Fengguang Wu <fengguang.wu@intel.com>,
H Peter Anvin <hpa@zytor.com>, Linux-X86 <x86@kernel.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 5/5] mm: x86: Revisit tlb_flushall_shift tuning for page flushes except on IvyBridge
Date: Thu, 09 Jan 2014 15:00:51 -0500 [thread overview]
Message-ID: <52CEFFF3.9010709@redhat.com> (raw)
In-Reply-To: <1389278098-27154-6-git-send-email-mgorman@suse.de>
On 01/09/2014 09:34 AM, Mel Gorman wrote:
> There was a large ebizzy performance regression that was bisected to commit
> 611ae8e3 (x86/tlb: enable tlb flush range support for x86). The problem
> was related to the tlb_flushall_shift tuning for IvyBridge which was
> altered. The problem is that it is not clear if the tuning values for each
> CPU family is correct as the methodology used to tune the values is unclear.
>
> This patch uses a conservative tlb_flushall_shift value for all CPU families
> except IvyBridge so the decision can be revisited if any regression is found
> as a result of this change. IvyBridge is an exception as testing with one
> methodology determined that the value of 2 is acceptable. Details are in the
> changelog for the patch "x86: mm: Change tlb_flushall_shift for IvyBridge".
>
> One important aspect of this to watch out for is Xen. The original commit
> log mentioned large performance gains on Xen. It's possible Xen is more
> sensitive to this value if it flushes small ranges of pages more frequently
> than workloads on bare metal typically do.
>
> Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
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next prev parent reply other threads:[~2014-01-09 20:01 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-09 14:34 [PATCH 0/5] Fix ebizzy performance regression due to X86 TLB range flush v3 Mel Gorman
2014-01-09 14:34 ` [PATCH 1/5] x86: mm: Account for TLB flushes only when debugging Mel Gorman
2014-01-09 19:43 ` Rik van Riel
2014-01-16 11:12 ` [PATCH] mm: vmstat: Do not display stats for TLB flushes unless debugging Mel Gorman
2014-01-16 12:25 ` Rik van Riel
2014-01-16 23:22 ` David Rientjes
2014-01-17 8:53 ` Mel Gorman
2014-01-09 14:34 ` [PATCH 2/5] x86: mm: Clean up inconsistencies when flushing TLB ranges Mel Gorman
2014-01-09 19:47 ` Rik van Riel
2014-01-09 14:34 ` [PATCH 3/5] x86: mm: Eliminate redundant page table walk during TLB range flushing Mel Gorman
2014-01-09 19:49 ` Rik van Riel
2014-01-09 14:34 ` [PATCH 4/5] x86: mm: Change tlb_flushall_shift for IvyBridge Mel Gorman
2014-01-09 19:59 ` Rik van Riel
2014-01-09 14:34 ` [PATCH 5/5] mm: x86: Revisit tlb_flushall_shift tuning for page flushes except on IvyBridge Mel Gorman
2014-01-09 20:00 ` Rik van Riel [this message]
2014-01-09 21:39 ` [PATCH 0/5] Fix ebizzy performance regression due to X86 TLB range flush v3 Davidlohr Bueso
2014-01-16 14:01 ` [TLB range flush] +34.7% hackbench.throughput Fengguang Wu
2014-01-16 18:49 ` Mel Gorman
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