From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 27 Sep 2007 15:59:07 -0700 From: Andrew Morton Subject: Re: [PATCH] kswapd should only wait on IO if there is IO Message-Id: <20070927155907.a4dce0d8.akpm@linux-foundation.org> In-Reply-To: <20070927185027.1a1b4c13@bree.surriel.com> References: <20070927170816.055548fd@bree.surriel.com> <20070927144702.a9124c7a.akpm@linux-foundation.org> <20070927181325.21aae460@bree.surriel.com> <20070927152121.3f5b6830.akpm@linux-foundation.org> <20070927185027.1a1b4c13@bree.surriel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Rik van Riel Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Thu, 27 Sep 2007 18:50:27 -0400 Rik van Riel wrote: > On Thu, 27 Sep 2007 15:21:21 -0700 > Andrew Morton wrote: > > > > Nope, sc.nr_io_pages will also be incremented when the code runs into > > > pages that are already PageWriteback. > > > > yup, I didn't think of that. Hopefully someone else will be in there > > working on that zone too. If this caller yields and defers to kswapd > > then that's very likely. Except we just took away the ability to do that.. > > if (PageDirty(page)) { > if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced) > goto keep_locked; > if (!may_enter_fs) > goto keep_locked; > > I think we can fix that problem by adding a sc->nr_io_pages++ > between the last if and the goto keep_locked in shrink_page_list. > > That way !GFP_IO or !GFP_FS tasks will cause themselves to sleep > if there are pages that need to be written out, even if those > pages are not in flight to disk yet. yeah, that's prudent I guess. > I have also added the comment you wanted. And lost the changelog ;) > - if (sc.nr_scanned && priority < DEF_PRIORITY - 2) > + if (sc.nr_scanned && priority < DEF_PRIORITY - 2 && > + sc.nr_io_pages > sc.swap_cluster_max) I do think this design decision needs a bit of explanation too. > congestion_wait(WRITE, HZ/10); > } > /* top priority shrink_caches still had more to do? don't OOM, then */ > @@ -1315,6 +1330,7 @@ loop_again: > if (!priority) > disable_swap_token(); > > + sc.nr_io_pages = 0; > all_zones_ok = 1; > > /* > @@ -1398,7 +1414,8 @@ loop_again: > * OK, kswapd is getting into trouble. Take a nap, then take > * another pass across the zones. > */ > - if (total_scanned && priority < DEF_PRIORITY - 2) > + if (total_scanned && priority < DEF_PRIORITY - 2 && As did that one. Ho hum :( Maybe it's in the git history somewhere. -- 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