linux-kernel - Re: [PATCH mmotm 2.5/4] memcg: disable irq at page cgroup lock (Re: [PATCH -mmotm 3/4] memcg: dirty pages accounting and limiting infrastructure)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 10 Mar 2010 09:26:24 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	Daisuke Nishimura <nishimura@....nes.nec.co.jp>
Cc:	linux-mm@...ck.org, Andrea Righi <arighi@...eler.com>,
	linux-kernel@...r.kernel.org,
	Trond Myklebust <trond.myklebust@....uio.no>,
	Suleiman Souhlal <suleiman@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	containers@...ts.linux-foundation.org,
	Vivek Goyal <vgoyal@...hat.com>
Subject: Re: [PATCH mmotm 2.5/4] memcg: disable irq at page cgroup lock (Re:
 [PATCH -mmotm 3/4] memcg: dirty pages accounting and limiting
 infrastructure)

* nishimura@....nes.nec.co.jp <nishimura@....nes.nec.co.jp> [2010-03-10 10:43:09]:

> > Please please measure the performance overhead of this change.
> > 
> 
> here.
> 
> > > > > > > I made a patch below and measured the time(average of 10 times) of kernel build
> > > > > > > on tmpfs(make -j8 on 8 CPU machine with 2.6.33 defconfig).
> > > > > > > 
> > > > > > > <before>
> > > > > > > - root cgroup: 190.47 sec
> > > > > > > - child cgroup: 192.81 sec
> > > > > > > 
> > > > > > > <after>
> > > > > > > - root cgroup: 191.06 sec
> > > > > > > - child cgroup: 193.06 sec
> > > > > > > 
> 
> <after2(local_irq_save/restore)>
> - root cgroup: 191.42 sec
> - child cgroup: 193.55 sec
> 
> hmm, I think it's in error range, but I can see a tendency by testing several times
> that it's getting slower as I add additional codes. Using local_irq_disable()/enable()
> except in mem_cgroup_update_file_mapped(it can be the only candidate to be called
> with irq disabled in future) might be the choice.
>

Error range would depend on things like standard deviation and
repetition. It might be good to keep update_file_mapped and see the
impact. My concern is with large systems, the difference might be
larger.
 
-- 
	Three Cheers,
	Balbir
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/