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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id D0E7EC77B6F for ; Tue, 11 Apr 2023 15:03:16 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pmFWU-0003Qc-Du; Tue, 11 Apr 2023 11:03:06 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pmFWH-0003EE-06 for qemu-devel@nongnu.org; Tue, 11 Apr 2023 11:02:54 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pmFW7-00028t-Sk for qemu-devel@nongnu.org; Tue, 11 Apr 2023 11:02:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681225335; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3DiKYu/rfwadYrMp66jxWIw+7QboZ3iGXwOVy15XVMs=; b=JyHO1ACTDRV8/LnkGnvgyum1jaZ1UtahpH5I2XCzY2aiax3zZvfK/bJ2W9AETUXyDGPRei vQDlFb1xWHUwxCmm+4cQNicOE50GN8d+NGARhS1NHIbftPeRy2oGZbC/bQHTKF0ymlnEys R6Tu1W5H4ik4tM5gxr/Q7B4jKEQ2th4= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-483-6qw5lKC5NtOX5XyP-8jt4A-1; Tue, 11 Apr 2023 11:02:13 -0400 X-MC-Unique: 6qw5lKC5NtOX5XyP-8jt4A-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 60D38280049C; Tue, 11 Apr 2023 15:02:13 +0000 (UTC) Received: from merkur.fritz.box (unknown [10.39.193.156]) by smtp.corp.redhat.com (Postfix) with ESMTP id AA23F40BC797; Tue, 11 Apr 2023 15:02:12 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org Subject: [PULL 10/10] block, block-backend: write some hot coroutine wrappers by hand Date: Tue, 11 Apr 2023 17:01:47 +0200 Message-Id: <20230411150147.318637-11-kwolf@redhat.com> In-Reply-To: <20230411150147.318637-1-kwolf@redhat.com> References: <20230411150147.318637-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Paolo Bonzini The introduction of the graph lock is causing blk_get_geometry, a hot function used in the I/O path, to create a coroutine. However, the only part that really needs to run in coroutine context is the call to bdrv_co_refresh_total_sectors, which in turn only happens in the rare case of host CD-ROM devices. So, write by hand the three wrappers on the path from blk_co_get_geometry to bdrv_co_refresh_total_sectors, so that the coroutine wrapper is only created if bdrv_nb_sectors actually calls bdrv_refresh_total_sectors. Reported-by: Stefan Hajnoczi Signed-off-by: Paolo Bonzini Message-Id: <20230407153303.391121-9-pbonzini@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- include/block/block-io.h | 2 +- include/sysemu/block-backend-io.h | 5 ++--- block.c | 22 ++++++++++++++++++++++ block/block-backend.c | 27 +++++++++++++++++++++++++++ 4 files changed, 52 insertions(+), 4 deletions(-) diff --git a/include/block/block-io.h b/include/block/block-io.h index 9e2248a295..5dab88521d 100644 --- a/include/block/block-io.h +++ b/include/block/block-io.h @@ -79,7 +79,7 @@ bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact, PreallocMode prealloc, BdrvRequestFlags flags, Error **errp); int64_t coroutine_fn GRAPH_RDLOCK bdrv_co_nb_sectors(BlockDriverState *bs); -int64_t co_wrapper_mixed_bdrv_rdlock bdrv_nb_sectors(BlockDriverState *bs); +int64_t coroutine_mixed_fn bdrv_nb_sectors(BlockDriverState *bs); int64_t coroutine_fn GRAPH_RDLOCK bdrv_co_getlength(BlockDriverState *bs); int64_t co_wrapper_mixed_bdrv_rdlock bdrv_getlength(BlockDriverState *bs); diff --git a/include/sysemu/block-backend-io.h b/include/sysemu/block-backend-io.h index c672b77247..bb25493ba1 100644 --- a/include/sysemu/block-backend-io.h +++ b/include/sysemu/block-backend-io.h @@ -72,11 +72,10 @@ int64_t co_wrapper_mixed blk_getlength(BlockBackend *blk); void coroutine_fn blk_co_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr); -void co_wrapper_mixed blk_get_geometry(BlockBackend *blk, - uint64_t *nb_sectors_ptr); +void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr); int64_t coroutine_fn blk_co_nb_sectors(BlockBackend *blk); -int64_t co_wrapper_mixed blk_nb_sectors(BlockBackend *blk); +int64_t blk_nb_sectors(BlockBackend *blk); void *blk_try_blockalign(BlockBackend *blk, size_t size); void *blk_blockalign(BlockBackend *blk, size_t size); diff --git a/block.c b/block.c index e8e08ad668..d79a52ca74 100644 --- a/block.c +++ b/block.c @@ -5859,6 +5859,28 @@ int64_t coroutine_fn bdrv_co_nb_sectors(BlockDriverState *bs) return bs->total_sectors; } +/* + * This wrapper is written by hand because this function is in the hot I/O path, + * via blk_get_geometry. + */ +int64_t coroutine_mixed_fn bdrv_nb_sectors(BlockDriverState *bs) +{ + BlockDriver *drv = bs->drv; + IO_CODE(); + + if (!drv) + return -ENOMEDIUM; + + if (bs->bl.has_variable_length) { + int ret = bdrv_refresh_total_sectors(bs, bs->total_sectors); + if (ret < 0) { + return ret; + } + } + + return bs->total_sectors; +} + /** * Return length in bytes on success, -errno on error. * The length is always a multiple of BDRV_SECTOR_SIZE. diff --git a/block/block-backend.c b/block/block-backend.c index cf58d4d1b7..55efc735b4 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -1629,6 +1629,23 @@ int64_t coroutine_fn blk_co_nb_sectors(BlockBackend *blk) } } +/* + * This wrapper is written by hand because this function is in the hot I/O path, + * via blk_get_geometry. + */ +int64_t coroutine_mixed_fn blk_nb_sectors(BlockBackend *blk) +{ + BlockDriverState *bs = blk_bs(blk); + + IO_CODE(); + + if (!bs) { + return -ENOMEDIUM; + } else { + return bdrv_nb_sectors(bs); + } +} + /* return 0 as number of sectors if no device present or error */ void coroutine_fn blk_co_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr) @@ -1637,6 +1654,16 @@ void coroutine_fn blk_co_get_geometry(BlockBackend *blk, *nb_sectors_ptr = ret < 0 ? 0 : ret; } +/* + * This wrapper is written by hand because this function is in the hot I/O path. + */ +void coroutine_mixed_fn blk_get_geometry(BlockBackend *blk, + uint64_t *nb_sectors_ptr) +{ + int64_t ret = blk_nb_sectors(blk); + *nb_sectors_ptr = ret < 0 ? 0 : ret; +} + BlockAIOCB *blk_aio_preadv(BlockBackend *blk, int64_t offset, QEMUIOVector *qiov, BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque) -- 2.39.2