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
| ||
|
Date: Thu, 12 May 2011 20:18:31 +0200 From: Andrea Arcangeli <aarcange@...hat.com> To: Christoph Lameter <cl@...ux.com> Cc: James Bottomley <James.Bottomley@...senPartnership.com>, Dave Jones <davej@...hat.com>, Mel Gorman <mgorman@...e.de>, Andrew Morton <akpm@...ux-foundation.org>, Colin King <colin.king@...onical.com>, Raghavendra D Prabhu <raghu.prabhu13@...il.com>, Jan Kara <jack@...e.cz>, Chris Mason <chris.mason@...cle.com>, Pekka Enberg <penberg@...nel.org>, Rik van Riel <riel@...hat.com>, Johannes Weiner <hannes@...xchg.org>, linux-fsdevel <linux-fsdevel@...r.kernel.org>, linux-mm <linux-mm@...ck.org>, linux-kernel <linux-kernel@...r.kernel.org>, linux-ext4 <linux-ext4@...r.kernel.org> Subject: Re: [PATCH 3/3] mm: slub: Default slub_max_order to 0 On Thu, May 12, 2011 at 01:00:10PM -0500, Christoph Lameter wrote: > On Thu, 12 May 2011, Andrea Arcangeli wrote: > > > order 1 should work better, because it's less likely we end up here > > (which leaves RECLAIM_MODE_LUMPYRECLAIM on and then see what happens > > at the top of page_check_references()) > > > > else if (sc->order && priority < DEF_PRIORITY - 2) > > Why is this DEF_PRIORITY - 2? Shouldnt it be DEF_PRIORITY? An accomodation > for SLAB order 1 allocs? That's to allow a few loops of the shrinker (i.e. not take down everything in the way regardless of any aging information in pte/page if there's no memory pressure). This "- 2" is independent of the allocation order. If it was < DEF_PRIORITY it'd trigger lumpy already at the second loop (in do_try_to_free_pages). So it'd make things worse. Like it'd make things worse decreasing the PAGE_ALLOC_COSTLY_ORDER define to 2 and keeping slub at 3. > May I assume that the case of order 2 and 3 allocs in that case was not > very well tested after the changes to introduce compaction since people > were focusing on RHEL testing? Not really, I had to eliminate lumpy before compaction was developed. RHEL6 has zero lumpy code (not even at compile time) and compaction enabled by default, so even if we enabled SLUB=y it should work ok (not sure why James still crashes with patch 2 applied that clears __GFP_WAIT, that crash likely has nothing to do with compaction or lumpy as both are off with __GFP_WAIT not set). Lumpy is also eliminated upstream now (but only at runtime when COMPACTION=y), unless __GFP_REPEAT is set, in which case I think lumpy will still work upstream too but few unfrequent things like increasing nr_hugepages uses that. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists