From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 4 Oct 2007 11:54:58 -0700 From: Andrew Morton Subject: Re: [PATCH] remove throttle_vm_writeout() Message-Id: <20071004115458.10897e51.akpm@linux-foundation.org> In-Reply-To: <1191521410.5574.36.camel@lappy> References: <1191501626.22357.14.camel@twins> <1191504186.22357.20.camel@twins> <1191516427.5574.7.camel@lappy> <20071004104650.d158121f.akpm@linux-foundation.org> <1191521410.5574.36.camel@lappy> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: miklos@szeredi.hu, wfg@mail.ustc.edu.cn, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Thu, 04 Oct 2007 20:10:10 +0200 Peter Zijlstra wrote: > > On Thu, 2007-10-04 at 10:46 -0700, Andrew Morton wrote: > > On Thu, 04 Oct 2007 18:47:07 +0200 Peter Zijlstra wrote: > > > > static int may_write_to_queue(struct backing_dev_info *bdi) > > > { > > > if (current->flags & PF_SWAPWRITE) > > > return 1; > > > if (!bdi_write_congested(bdi)) > > > return 1; > > > if (bdi == current->backing_dev_info) > > > return 1; > > > return 0; > > > } > > > > > > Which will write to congested queues. Anybody know why? > > OK, I guess I could have found that :-/ Nice changelog, if I do say so myself ;) > > One fix for this would be to add an additional "really congested" > > threshold in the request queues, so kswapd can still perform > > nonblocking writeout. This gives kswapd priority over pdflush while > > allowing kswapd to feed many disk queues. I doubt if this will be > > called for. > > I could do that. I guess first you'd need to be able to reproduce the problem which that patch fixed, then check that it remains fixed. Sigh. That problem was fairly subtle. We could re-break reclaim in this way and not find out about it for six months. There's a lesson here. Several. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org