From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f48.google.com (mail-pa0-f48.google.com [209.85.220.48]) by kanga.kvack.org (Postfix) with ESMTP id 468C16B0035 for ; Thu, 29 May 2014 06:39:29 -0400 (EDT) Received: by mail-pa0-f48.google.com with SMTP id rd3so167418pab.7 for ; Thu, 29 May 2014 03:39:28 -0700 (PDT) Received: from ipmail06.adl6.internode.on.net (ipmail06.adl6.internode.on.net. [2001:44b8:8060:ff02:300:1:6:6]) by mx.google.com with ESMTP id fu6si377930pac.106.2014.05.29.03.39.27 for ; Thu, 29 May 2014 03:39:28 -0700 (PDT) Date: Thu, 29 May 2014 20:39:05 +1000 From: Dave Chinner Subject: Re: virtio ring cleanups, which save stack on older gcc Message-ID: <20140529103905.GQ8554@dastard> References: <87oayh6s3s.fsf@rustcorp.com.au> <1401348405-18614-1-git-send-email-rusty@rustcorp.com.au> <20140529074117.GI10092@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140529074117.GI10092@bbox> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Rusty Russell , Linus Torvalds , Jens Axboe , Linux Kernel Mailing List , Andrew Morton , linux-mm , "H. Peter Anvin" , Ingo Molnar , Peter Zijlstra , Mel Gorman , Rik van Riel , Johannes Weiner , Hugh Dickins , "Michael S. Tsirkin" , Dave Hansen , Steven Rostedt On Thu, May 29, 2014 at 04:41:17PM +0900, Minchan Kim wrote: > Hello Rusty, > > On Thu, May 29, 2014 at 04:56:41PM +0930, Rusty Russell wrote: > > They don't make much difference: the easier fix is use gcc 4.8 > > which drops stack required across virtio block's virtio_queue_rq > > down to that kmalloc in virtio_ring from 528 to 392 bytes. > > > > Still, these (*lightly tested*) patches reduce to 432 bytes, > > even for gcc 4.6.4. Posted here FYI. > > I am testing with below which was hack for Dave's idea so don't have > a machine to test your patches until tomorrow. > So, I will queue your patches into testing machine tomorrow morning. > > Thanks! > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index f5c6635b806c..95f169e85dbe 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -4241,10 +4241,13 @@ EXPORT_SYMBOL_GPL(yield_to); > void __sched io_schedule(void) > { > struct rq *rq = raw_rq(); > + struct blk_plug *plug = current->plug; > > delayacct_blkio_start(); > atomic_inc(&rq->nr_iowait); > - blk_flush_plug(current); > + if (plug) > + blk_flush_plug_list(plug, true); > + Could simply be - blk_flush_plug(current); + blk_schedule_flush_plug(current); Cheers, Dave. -- Dave Chinner david@fromorbit.com -- 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