From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8FB78C433DF for ; Wed, 20 May 2020 14:10:43 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 50252207D4 for ; Wed, 20 May 2020 14:10:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Bejq+Ge0" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 50252207D4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:45372 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jbPQg-0007a1-GM for qemu-devel@archiver.kernel.org; Wed, 20 May 2020 10:10:42 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:55058) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jbPLe-0007xv-Sr for qemu-devel@nongnu.org; Wed, 20 May 2020 10:05:30 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:38553 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jbPLd-0001fb-6k for qemu-devel@nongnu.org; Wed, 20 May 2020 10:05:30 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1589983527; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=HW6+1idwnzLIjuN55Bz9021whtxViyodRLk3cZK/Qfc=; b=Bejq+Ge0YMarWlxvttEWWG1V1Pz21r4fE7sntyoe1mwNSfyu9Zrl6TckTx9+zqrGSFpL6+ ftiMkpSneQ4mG3HTzKiiuQz8hPSxe20NseSH+Hbb5pFKA7pbXbuEfu+7LEeaCoZrwTMb2I gSECRBXgr1nhree0/pvH5zyqBHwIi60= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-190-6F6MqhE7MCuDBLMO1YVNJQ-1; Wed, 20 May 2020 10:05:25 -0400 X-MC-Unique: 6F6MqhE7MCuDBLMO1YVNJQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 740AC1085950; Wed, 20 May 2020 14:05:24 +0000 (UTC) Received: from linux.fritz.box (ovpn-115-47.ams2.redhat.com [10.36.115.47]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D16085D9E4; Wed, 20 May 2020 14:05:01 +0000 (UTC) Date: Wed, 20 May 2020 16:05:00 +0200 From: Kevin Wolf To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH v2] block: Factor out bdrv_run_co() Message-ID: <20200520140500.GB5192@linux.fritz.box> References: <20200519175650.31506-1-vsementsov@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: <20200519175650.31506-1-vsementsov@virtuozzo.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/20 02:22:41 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fam@euphon.net, qemu-block@nongnu.org, qemu-devel@nongnu.org, mreitz@redhat.com, stefanha@redhat.com, den@openvz.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 19.05.2020 um 19:56 hat Vladimir Sementsov-Ogievskiy geschrieben: > We have a few bdrv_*() functions that can either spawn a new coroutine > and wait for it with BDRV_POLL_WHILE() or use a fastpath if they are > alreeady running in a coroutine. All of them duplicate basically the > same code. > > Factor the common code into a new function bdrv_run_co(). > > Signed-off-by: Kevin Wolf > Signed-off-by: Vladimir Sementsov-Ogievskiy > [Factor out bdrv_run_co_entry too] > --- > > Hi! > > I'm a bit lost on rebasing "block/io: safer inc/dec in_flight sections" > (is it needed or not?), so, I decided to send just this one patch: > > I suggest to go a bit further, and refactor that bdrv_run_co don't need > additional *ret argument neither NOT_DONE logic. Hm, this approach adds another indirection and bdrv_pread/pwrite still seems to be on some hot paths. But maybe this is just the right motivation to clean up qcow2 a bit and use explicit bdrv_co_*() where it is possible. I might take a look later. > block/io.c | 191 ++++++++++++++++++++--------------------------------- > 1 file changed, 70 insertions(+), 121 deletions(-) > > diff --git a/block/io.c b/block/io.c > index 121ce17a49..794eebbd0c 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -35,8 +35,6 @@ > #include "qemu/main-loop.h" > #include "sysemu/replay.h" > > -#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */ > - > /* Maximum bounce buffer for copy-on-read and write zeroes, in bytes */ > #define MAX_BOUNCE_BUFFER (32768 << BDRV_SECTOR_BITS) > > @@ -891,29 +889,61 @@ static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset, > return 0; > } > > +typedef int coroutine_fn BdrvRequestEntry(void *opaque); > +typedef struct BdrvRunCo { > + BdrvRequestEntry *entry; > + void *opaque; > + int ret; > + bool done; > +} BdrvRunCo; > + > +static void coroutine_fn bdrv_run_co_entry(void *opaque) > +{ > + BdrvRunCo *arg = opaque; > + > + arg->ret = arg->entry(arg->opaque); > + arg->done = true; > + aio_wait_kick(); > +} > + > +static int bdrv_run_co(BlockDriverState *bs, BdrvRequestEntry *entry, > + void *opaque) > +{ > + if (qemu_in_coroutine()) { > + /* Fast-path if already in coroutine context */ > + return entry(opaque); > + } else { > + BdrvRunCo s = { .entry = entry, .opaque = opaque }; > + > + bdrv_coroutine_enter(bs, qemu_coroutine_create(bdrv_run_co_entry, &s)); Let's keep the coroutine in a separate variable, maybe inside BdrvRunCo. It's important for debugging BDRV_POLL_WHILE() hangs in gdb. > + > + BDRV_POLL_WHILE(bs, !s.done); > + > + return s.ret; > + } > +} Kevin