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 3/5] x86: mm: Eliminate redundant page table walk during TLB range flushing
Date: Thu, 09 Jan 2014 14:49:35 -0500 [thread overview]
Message-ID: <52CEFD4F.3080804@redhat.com> (raw)
In-Reply-To: <1389278098-27154-4-git-send-email-mgorman@suse.de>
On 01/09/2014 09:34 AM, Mel Gorman wrote:
> When choosing between doing an address space or ranged flush, the x86
> implementation of flush_tlb_mm_range takes into account whether there are
> any large pages in the range. A per-page flush typically requires fewer
> entries than would covered by a single large page and the check is redundant.
>
> There is one potential exception. THP migration flushes single THP entries
> and it conceivably would benefit from flushing a single entry instead
> of the mm. However, this flush is after a THP allocation, copy and page
> table update potentially with any other threads serialised behind it. In
> comparison to that, the flush is noise. It makes more sense to optimise
> balancing to require fewer flushes than to optimise the flush itself.
>
> This patch deletes the redundant huge page check.
>
> Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
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WARNING: multiple messages have this Message-ID (diff)
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 3/5] x86: mm: Eliminate redundant page table walk during TLB range flushing
Date: Thu, 09 Jan 2014 14:49:35 -0500 [thread overview]
Message-ID: <52CEFD4F.3080804@redhat.com> (raw)
In-Reply-To: <1389278098-27154-4-git-send-email-mgorman@suse.de>
On 01/09/2014 09:34 AM, Mel Gorman wrote:
> When choosing between doing an address space or ranged flush, the x86
> implementation of flush_tlb_mm_range takes into account whether there are
> any large pages in the range. A per-page flush typically requires fewer
> entries than would covered by a single large page and the check is redundant.
>
> There is one potential exception. THP migration flushes single THP entries
> and it conceivably would benefit from flushing a single entry instead
> of the mm. However, this flush is after a THP allocation, copy and page
> table update potentially with any other threads serialised behind it. In
> comparison to that, the flush is noise. It makes more sense to optimise
> balancing to require fewer flushes than to optimise the flush itself.
>
> This patch deletes the redundant huge page check.
>
> Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
next prev parent reply other threads:[~2014-01-09 20:12 UTC|newest]
Thread overview: 35+ 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 ` Mel Gorman
2014-01-09 14:34 ` [PATCH 1/5] x86: mm: Account for TLB flushes only when debugging Mel Gorman
2014-01-09 14:34 ` Mel Gorman
2014-01-09 19:43 ` Rik van Riel
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 11:12 ` Mel Gorman
2014-01-16 12:25 ` Rik van Riel
2014-01-16 12:25 ` Rik van Riel
2014-01-16 23:22 ` David Rientjes
2014-01-16 23:22 ` David Rientjes
2014-01-17 8:53 ` Mel Gorman
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 14:34 ` Mel Gorman
2014-01-09 19:47 ` Rik van Riel
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 14:34 ` Mel Gorman
2014-01-09 19:49 ` Rik van Riel [this message]
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 14:34 ` Mel Gorman
2014-01-09 19:59 ` Rik van Riel
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 14:34 ` Mel Gorman
2014-01-09 20:00 ` Rik van Riel
2014-01-09 20:00 ` Rik van Riel
2014-01-09 21:39 ` [PATCH 0/5] Fix ebizzy performance regression due to X86 TLB range flush v3 Davidlohr Bueso
2014-01-09 21:39 ` Davidlohr Bueso
2014-01-16 14:01 ` [TLB range flush] +34.7% hackbench.throughput Fengguang Wu
2014-01-16 18:49 ` Mel Gorman
2014-01-16 18:49 ` Mel Gorman
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