Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753441Ab3IZTxW (ORCPT ); Thu, 26 Sep 2013 15:53:22 -0400 Received: from mail-qe0-f48.google.com ([209.85.128.48]:52862 "EHLO mail-qe0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751037Ab3IZTxR (ORCPT ); Thu, 26 Sep 2013 15:53:17 -0400 MIME-Version: 1.0 X-Originating-IP: [86.59.245.170] In-Reply-To: <20130926190611.GP30372@lenny.home.zabbo.net> References: <1378919210-10372-1-git-send-email-zab@redhat.com> <20130925183828.GA30372@lenny.home.zabbo.net> <20130925190620.GB30372@lenny.home.zabbo.net> <20130925195526.GA18971@fieldses.org> <20130925210742.GG30372@lenny.home.zabbo.net> <20130926153359.GE704@fieldses.org> <20130926190611.GP30372@lenny.home.zabbo.net> Date: Thu, 26 Sep 2013 21:53:16 +0200 Message-ID: Subject: Re: [RFC] extending splice for copy offloading From: Miklos Szeredi To: Zach Brown Cc: "J. Bruce Fields" , Anna Schumaker , Kernel Mailing List , Linux-Fsdevel , "linux-nfs@vger.kernel.org" , Trond Myklebust , Bryan Schumaker , "Martin K. Petersen" , Jens Axboe , Mark Fasheh , Joel Becker , Eric Wong Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1203 Lines: 26 On Thu, Sep 26, 2013 at 9:06 PM, Zach Brown wrote: >> But I'm not sure it's worth the effort; 99% of the use of this >> interface will be copying whole files. And for that perhaps we need a >> different API, one which has been discussed some time ago: >> asynchronous copyfile() returns immediately with a pollable event >> descriptor indicating copy progress, and some way to cancel the copy. >> And that can internally rely on ->direct_splice(), with appropriate >> algorithms for determine the optimal chunk size. > > And perhaps we don't. Perhaps we can provide this much simpler > data-plane interface that works well enough for most everyone and can > avoid going down the async rat hole, yet again. I think either buffering or async is needed to get good perforrmace without too much complexity in the app (which is not good). Buffering works quite well for regular I/O, so maybe its the way to go here as well. Thanks, Miklos -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/