linux-kernel - Re: [PATCH] SLUB: revert direct page allocator pass through

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:	Sat, 24 Jan 2009 02:12:57 +1100
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Christoph Lameter <cl@...ux-foundation.org>
Cc:	Pekka J Enberg <penberg@...helsinki.fi>,
	yanmin_zhang@...ux.intel.com, Andi Kleen <andi@...stfloor.org>,
	Matthew Wilcox <matthew@....cx>, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org
Subject: Re: [PATCH] SLUB: revert direct page allocator pass through

On Saturday 24 January 2009 02:03:22 Christoph Lameter wrote:
> On Fri, 23 Jan 2009, Nick Piggin wrote:
> > Hmm, it lists quite a number of advantages that I guess are being
> > reverted too? What was the test case(s) that prompted this commit
> > in the first place? Better ensure it doesn't slow down...
>
> The advantage was mainly memory savings and abilty to redefined kmallocs
> to go directly to the page allocator. Totally avoids slab allocator
> overhead.

Well it sounds in the changelog like a massive performance advantage.
Unfortunately it doesn't really say what the workload was.


> I thought higher order allocations were not supposed to be used in
> performance critical paths?

? You use them all the time in SLUB alone.


> Didnt you want to do everything with order-0
> allocs?

People don't always do what I think is best, unfortunately ;)


> It seems that we currently need the slab allocators to compensate for the
> performance problems in the page allocator for these higher order allocs.
> I'd rather have the page allocator fixed but things are as they are.

No objections from me with speeding up the page allocator of course.


--
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/