linux-kernel - Re: [PATCH 1/2] Make the batch size of the percpu

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]

Message-ID: <1367345403.11020.1.camel@edumazet-glaptop>
Date:	Tue, 30 Apr 2013 11:10:03 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Tim Chen <tim.c.chen@...ux.intel.com>
Cc:	Christoph Lameter <cl@...ux.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>, Al Viro <viro@...iv.linux.org.uk>,
	Dave Hansen <dave.hansen@...el.com>,
	Andi Kleen <ak@...ux.intel.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>
Subject: Re: [PATCH 1/2] Make the batch size of the percpu_counter
 configurable

On Tue, 2013-04-30 at 09:23 -0700, Tim Chen wrote:
> On Tue, 2013-04-30 at 13:32 +0000, Christoph Lameter wrote:
> > On Mon, 29 Apr 2013, Tim Chen wrote:
> > 
> > > diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
> > > index d5dd465..5ca7df5 100644
> > > --- a/include/linux/percpu_counter.h
> > > +++ b/include/linux/percpu_counter.h
> > > @@ -22,6 +22,7 @@ struct percpu_counter {
> > >  	struct list_head list;	/* All percpu_counters are on a list */
> > >  #endif
> > >  	s32 __percpu *counters;
> > > +	int *batch ____cacheline_aligned_in_smp;
> > >  };
> > 
> > What is this for and why does it have that alignmend?
> 
> I was assuming that if batch is frequently referenced, it probably
> should not share a cache line with the counters field.

But 'counters' field has the same requirement. Its supposed to be read
only field. 

So please remove this '____cacheline_aligned_in_smp', as it makes the
whole struct percpu_counter at least two cache lines wide, for no
obvious reason.




--
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/