From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f45.google.com (mail-pa0-f45.google.com [209.85.220.45]) by kanga.kvack.org (Postfix) with ESMTP id 36E006B0035 for ; Thu, 29 May 2014 07:09:11 -0400 (EDT) Received: by mail-pa0-f45.google.com with SMTP id ey11so202219pad.4 for ; Thu, 29 May 2014 04:09:10 -0700 (PDT) Received: from ozlabs.org (ozlabs.org. [103.22.144.67]) by mx.google.com with ESMTPS id bz3si457461pbd.157.2014.05.29.04.09.09 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 May 2014 04:09:09 -0700 (PDT) From: Rusty Russell Subject: Re: [PATCH 4/4] virtio_ring: unify direct/indirect code paths. In-Reply-To: <20140529075256.GZ30445@twins.programming.kicks-ass.net> References: <87oayh6s3s.fsf@rustcorp.com.au> <1401348405-18614-1-git-send-email-rusty@rustcorp.com.au> <1401348405-18614-5-git-send-email-rusty@rustcorp.com.au> <20140529075256.GZ30445@twins.programming.kicks-ass.net> Date: Thu, 29 May 2014 20:35:58 +0930 Message-ID: <87iooo7skp.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Linus Torvalds , Dave Chinner , Jens Axboe , Minchan Kim , Linux Kernel Mailing List , Andrew Morton , linux-mm , "H. Peter Anvin" , Ingo Molnar , Mel Gorman , Rik van Riel , Johannes Weiner , Hugh Dickins , "Michael S. Tsirkin" , Dave Hansen , Steven Rostedt Peter Zijlstra writes: > On Thu, May 29, 2014 at 04:56:45PM +0930, Rusty Russell wrote: >> Before: >> gcc 4.8.2: virtio_blk: stack used = 392 >> gcc 4.6.4: virtio_blk: stack used = 480 >> >> After: >> gcc 4.8.2: virtio_blk: stack used = 408 >> gcc 4.6.4: virtio_blk: stack used = 432 > > Is it worth it to make the good compiler worse? People are going to use > the newer GCC more as time goes on anyhow. No, but it's only 16 bytes of stack loss for a simplicity win: virtio_ring.c | 120 +++++++++++++++++++++------------------------------------- 1 file changed, 45 insertions(+), 75 deletions(-) Cheers, Rusty. -- 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