linux-kernel - Re: [PATCH 1/3] slub: set a criteria for slub node partial adding

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:	Tue, 13 Dec 2011 17:29:22 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Shaohua Li <shaohua.li@...el.com>
cc:	"Shi, Alex" <alex.shi@...el.com>, Christoph Lameter <cl@...ux.com>,
	"penberg@...nel.org" <penberg@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 1/3] slub: set a criteria for slub node partial adding

On Mon, 12 Dec 2011, Shaohua Li wrote:

> With the per-cpu partial list, I didn't see any workload which is still
> suffering from the list lock, so I suppose both the trashing approach
> and pick 25% used slab approach don't help.

This doesn't necessarily have anything to do with contention on list_lock, 
it has to do with the fact that ~99% of allocations come from the slowpath 
since the cpu slab only has one free object when it is activated, that's 
what the statistics indicated for kmalloc-256 and kmalloc-2k.  That's what 
I called "slab thrashing": the continual deactivation of the cpu slab and 
picking from the partial list that would only have one or two free objects 
causing the vast majority of allocations to require the slowpath.
--
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/