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, 4 Jan 2012 17:28:42 -0800
From:	Tejun Heo <tj@...nel.org>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Vivek Goyal <vgoyal@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>, avi@...hat.com,
	nate@...nel.net, cl@...ux-foundation.org, oleg@...hat.com,
	axboe@...nel.dk, linux-kernel@...r.kernel.org
Subject: Re: [PATCHSET] block, mempool, percpu: implement percpu mempool
 and fix blkcg percpu alloc deadlock

On Tue, Dec 27, 2011 at 04:41:02PM -0800, Tejun Heo wrote:
> Hello,
> 
> On Wed, Dec 28, 2011 at 09:14:02AM +0900, KAMEZAWA Hiroyuki wrote:
> > > This is essentially more specialized form of the mempool approach.  It
> > > doesn't seem any simpler to me while being less generic.  I don't see
> > > what the upside would be.
> > 
> > Hm, but this never causes -ENOMEM error, at all.
> 
> Ooh, I missed the part it falls back to the global counter if percpu
> counters aren't allocated yet.  Yeah, this is an interesting approach.
> I'll think more about it.

I've been staring at the blkcg stats code and commit logs and am
wondering whether we can just scrap percpu counters there.  It seems
the reason why it was introduced in the first place is to avoid
stats->lock, which BTW is extremely heavy handed for gathering stats,
overhead in fast paths and I think there can be easier ways to avoid
stats->lock.

Thanks.

-- 
tejun
--
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/

Powered by blists - more mailing lists