From: Markus Trippelsdorf <markus@trippelsdorf.de>
To: linux-mm@kvack.org
Cc: Vlastimil Babka <vbabka@suse.cz>
Subject: Re: isolate_freepages_block(): very high intermittent overhead
Date: Mon, 27 Oct 2014 22:06:56 +0100 [thread overview]
Message-ID: <20141027210656.GC348@x4> (raw)
In-Reply-To: <20141027204003.GB348@x4>
On 2014.10.27 at 21:40 +0100, Markus Trippelsdorf wrote:
> On my v3.18-rc2 kernel isolate_freepages_block() sometimes shows up very
> high (>20%) in perf top during the configuration phase of software
> builds. It increases build time considerably.
>
> Unfortunately the issue is not 100% reproducible, because it appears
> only intermittently. And the symptoms vanish after a few minutes.
>
> I think the "mm, compaction" series from Vlastimil is to blame, but it's
> hard to be sure when bisection doesn't work.
Here is an example:
Overhead Shared Object Symbol
59.12% [kernel] [k] isolate_freepages_block
4.75% [kernel] [k] amd_e400_idle
1.10% [kernel] [k] clear_page_c
0.89% [kernel] [k] get_pfnblock_flags_mask
0.64% ld-2.19.90.so [.] do_lookup_x
0.64% [kernel] [k] unmap_single_vma
0.58% [kernel] [k] copy_page_rep
0.54% libc-2.19.90.so [.] memcpy@@GLIBC_2.14
0.52% [kernel] [k] filemap_map_pages
0.47% [kernel] [k] _cond_resched
--
Markus
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next prev parent reply other threads:[~2014-10-27 21:06 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-27 20:40 isolate_freepages_block(): very high intermittent overhead Markus Trippelsdorf
2014-10-27 21:06 ` Markus Trippelsdorf [this message]
2014-10-27 22:01 ` Vlastimil Babka
2014-10-28 8:59 ` Markus Trippelsdorf
2014-10-29 15:08 ` Vlastimil Babka
2014-11-06 11:42 ` Vlastimil Babka
2014-11-06 11:53 ` Markus Trippelsdorf
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