From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:50859) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1REirU-0006Sc-3z for qemu-devel@nongnu.org; Fri, 14 Oct 2011 10:35:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1REirO-0006D2-Jx for qemu-devel@nongnu.org; Fri, 14 Oct 2011 10:35:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40172) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1REirO-0006Ct-CW for qemu-devel@nongnu.org; Fri, 14 Oct 2011 10:35:42 -0400 Message-ID: <4E9848B5.3020108@redhat.com> Date: Fri, 14 Oct 2011 16:35:33 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1318581692-18338-1-git-send-email-pbonzini@redhat.com> <1318581692-18338-5-git-send-email-pbonzini@redhat.com> <4E9845E6.3020905@redhat.com> <4E98463A.1010007@redhat.com> <4E984819.3010009@redhat.com> In-Reply-To: <4E984819.3010009@redhat.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 4/4] block: add bdrv_co_discard and bdrv_aio_discard support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: qemu-devel@nongnu.org, stefanha@linux.vnet.ibm.com On 10/14/2011 04:32 PM, Kevin Wolf wrote: > > I can certainly drop aio_discard from the backends, but I'm not sure how > > heavy can fallocate be (with FALLOC_FL_PUNCH_HOLE). Probably not much, > > but I think there's no guarantee of O(1) behavior especially with > > filesystems like ecryptfs. So you would need to go through the thread > > pool and aio_discard would come in handy. > > Sure, but the coroutine interface should be just as good for > implementing it this way in raw-posix. I think until someone rewrites raw_aio_submit/paio_submit in terms of coroutines, it's better to keep aio_discard. Paolo