From: Vlastimil Babka <vbabka@suse.cz>
To: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: linux-mm@kvack.org
Subject: Re: isolate_freepages_block(): very high intermittent overhead
Date: Wed, 29 Oct 2014 16:08:01 +0100 [thread overview]
Message-ID: <545102D1.6080908@suse.cz> (raw)
In-Reply-To: <20141028085916.GA337@x4>
On 10/28/2014 09:59 AM, Markus Trippelsdorf wrote:
> On 2014.10.27 at 23:01 +0100, Vlastimil Babka wrote:
>> On 10/27/2014 09:40 PM, 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.
>>
>> Does it happen for long enough so you can capture it by perf record -g ?
>
> It only happens when I use the "Lockless Allocator":
> http://locklessinc.com/downloads/lockless_allocator_src.tgz
>
> I use: LD_PRELOAD=/usr/lib/libllalloc.so.1.3 when building software,
> because it gives me a ~8% speed boost over glibc's malloc.
Hm I see. I'll try to test that.
> Unfortunately, I don't have time to debug this further and have disabled
> "Transparent Hugepage Support" for now.
That's unfortunate indeed. Commit
e14c720efdd73c6d69cd8d07fa894bcd11fe1973 "mm, compaction: remember
position within pageblock in free pages scanner" would be the most
suspicious one here I guess, so testing at least a kernel with this
patch reverted would be very useful. Simple git revert seems to apply
cleanly here.
Thanks,
Vlastimil
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next prev parent reply other threads:[~2014-10-29 15:08 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
2014-10-27 22:01 ` Vlastimil Babka
2014-10-28 8:59 ` Markus Trippelsdorf
2014-10-29 15:08 ` Vlastimil Babka [this message]
2014-11-06 11:42 ` Vlastimil Babka
2014-11-06 11:53 ` Markus Trippelsdorf
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