From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Piggin Subject: Re: [dm-devel] Re: [PATCH resubmit] do_mount: reduce stack consumption Date: Tue, 08 Nov 2005 11:32:13 +1100 Message-ID: <436FF20D.8030200@yahoo.com.au> References: <20051104105026.GA12476@osiris.boeblingen.de.ibm.com> <20051104084829.714c5dbb.akpm@osdl.org> <20051104212742.GC9222@osiris.ibm.com> <20051104235500.GE5368@stusta.de> <20051104160851.3a7463ff.akpm@osdl.org> <20051104173721.597bd223.akpm@osdl.org> <17260.17661.523593.420313@cse.unsw.edu.au> <17262.40176.342746.634262@cse.unsw.edu.au> <20051107153706.2f3c8b67.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20051107153706.2f3c8b67.akpm@osdl.org> Sender: linux-kernel-owner@vger.kernel.org To: Andrew Morton Cc: Neil Brown , dm-devel@redhat.com, heiko.carstens@de.ibm.com, linux-kernel@vger.kernel.org, aherrman@de.ibm.com, bunk@stusta.de, cplk@itee.uq.edu.au List-Id: dm-devel.ids Andrew Morton wrote: > Neil Brown wrote: > >>... >>Reduce stack usage with stacked block devices >> >>... >>diff ./include/linux/sched.h~current~ ./include/linux/sched.h >>--- ./include/linux/sched.h~current~ 2005-11-07 10:01:36.000000000 +1100 >>+++ ./include/linux/sched.h 2005-11-07 10:02:23.000000000 +1100 >>@@ -829,6 +829,9 @@ struct task_struct { >> /* journalling filesystem info */ >> void *journal_info; >> >>+/* stacked block device info */ >>+ struct bio *bio_list, **bio_tail; >>+ >> /* VM state */ >> struct reclaim_state *reclaim_state; >> > > > More state in the task_strut is a bit sad, but not nearly as sad as deep > recursion in our deepest codepath.. > > Possibly one could do: > > struct make_request_state { > struct bio *bio_list; > struct bio **bio_tail; > }; > > and stick a `struct make_request_state *' into the task_struct and actually > allocate the thing on the stack. That's not much nicer though. Possibly it could go into struct io_context? -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com