From patchwork Tue Jun 11 17:36:56 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 13694058 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 4AD23C27C75 for ; Tue, 11 Jun 2024 17:38:44 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sH5Qw-00008h-9I; Tue, 11 Jun 2024 13:37:22 -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 1sH5Qu-00007f-P9 for qemu-devel@nongnu.org; Tue, 11 Jun 2024 13:37:20 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sH5Qt-0008Ul-2K for qemu-devel@nongnu.org; Tue, 11 Jun 2024 13:37:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1718127438; 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=Pic+NTGR2xDZGvJdSIIWUg6ye59mZnjGjver02Rud84=; b=JNBSZ6KpPTXcX2sYEBJ7C9irFR3XhyG3rWxJ2d5TGAVjEDgK+yYs35rHY9pIKFIwNyDNaN 6f/UEoFOMg38Q87ZIMVuhiZ8EYBCO7c/rteAI1lZgD+95vQuQrLQDzAVu+uZYu9NfBbLZP 8TrwoC51hthba4SI6uUgHdvJ6ZY1v/U= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-170-FUDJC3w9OQaijwwYgsIhrA-1; Tue, 11 Jun 2024 13:37:16 -0400 X-MC-Unique: FUDJC3w9OQaijwwYgsIhrA-1 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id CEA7A19560BC; Tue, 11 Jun 2024 17:37:15 +0000 (UTC) Received: from merkur.fritz.box (unknown [10.39.192.130]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 9B38B19560AF; Tue, 11 Jun 2024 17:37:14 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [PULL 6/8] linux-aio: add IO_CMD_FDSYNC command support Date: Tue, 11 Jun 2024 19:36:56 +0200 Message-ID: <20240611173658.231831-7-kwolf@redhat.com> In-Reply-To: <20240611173658.231831-1-kwolf@redhat.com> References: <20240611173658.231831-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 11 X-Spam_score: 1.1 X-Spam_bar: + X-Spam_report: (1.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.141, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no 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: Prasad Pandit Libaio defines IO_CMD_FDSYNC command to sync all outstanding asynchronous I/O operations, by flushing out file data to the disk storage. Enable linux-aio to submit such aio request. When using aio=native without fdsync() support, QEMU creates pthreads, and destroying these pthreads results in TLB flushes. In a real-time guest environment, TLB flushes cause a latency spike. This patch helps to avoid such spikes. Reviewed-by: Stefan Hajnoczi Signed-off-by: Prasad Pandit Message-ID: <20240425070412.37248-1-ppandit@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- include/block/raw-aio.h | 1 + block/file-posix.c | 9 +++++++++ block/linux-aio.c | 21 ++++++++++++++++++++- 3 files changed, 30 insertions(+), 1 deletion(-) diff --git a/include/block/raw-aio.h b/include/block/raw-aio.h index 20e000b8ef..626706827f 100644 --- a/include/block/raw-aio.h +++ b/include/block/raw-aio.h @@ -60,6 +60,7 @@ void laio_cleanup(LinuxAioState *s); int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov, int type, uint64_t dev_max_batch); +bool laio_has_fdsync(int); void laio_detach_aio_context(LinuxAioState *s, AioContext *old_context); void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context); #endif diff --git a/block/file-posix.c b/block/file-posix.c index 5c46938936..be25e35ff6 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -159,6 +159,7 @@ typedef struct BDRVRawState { bool has_discard:1; bool has_write_zeroes:1; bool use_linux_aio:1; + bool has_laio_fdsync:1; bool use_linux_io_uring:1; int page_cache_inconsistent; /* errno from fdatasync failure */ bool has_fallocate; @@ -718,6 +719,9 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, ret = -EINVAL; goto fail; } + if (s->use_linux_aio) { + s->has_laio_fdsync = laio_has_fdsync(s->fd); + } #else if (s->use_linux_aio) { error_setg(errp, "aio=native was specified, but is not supported " @@ -2598,6 +2602,11 @@ static int coroutine_fn raw_co_flush_to_disk(BlockDriverState *bs) if (raw_check_linux_io_uring(s)) { return luring_co_submit(bs, s->fd, 0, NULL, QEMU_AIO_FLUSH); } +#endif +#ifdef CONFIG_LINUX_AIO + if (s->has_laio_fdsync && raw_check_linux_aio(s)) { + return laio_co_submit(s->fd, 0, NULL, QEMU_AIO_FLUSH, 0); + } #endif return raw_thread_pool_submit(handle_aiocb_flush, &acb); } diff --git a/block/linux-aio.c b/block/linux-aio.c index ec05d946f3..e3b5ec9aba 100644 --- a/block/linux-aio.c +++ b/block/linux-aio.c @@ -384,6 +384,9 @@ static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset, case QEMU_AIO_READ: io_prep_preadv(iocbs, fd, qiov->iov, qiov->niov, offset); break; + case QEMU_AIO_FLUSH: + io_prep_fdsync(iocbs, fd); + break; /* Currently Linux kernel does not support other operations */ default: fprintf(stderr, "%s: invalid AIO request type 0x%x.\n", @@ -412,7 +415,7 @@ int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov, AioContext *ctx = qemu_get_current_aio_context(); struct qemu_laiocb laiocb = { .co = qemu_coroutine_self(), - .nbytes = qiov->size, + .nbytes = qiov ? qiov->size : 0, .ctx = aio_get_linux_aio(ctx), .ret = -EINPROGRESS, .is_read = (type == QEMU_AIO_READ), @@ -486,3 +489,19 @@ void laio_cleanup(LinuxAioState *s) } g_free(s); } + +bool laio_has_fdsync(int fd) +{ + struct iocb cb; + struct iocb *cbs[] = {&cb, NULL}; + + io_context_t ctx = 0; + io_setup(1, &ctx); + + /* check if host kernel supports IO_CMD_FDSYNC */ + io_prep_fdsync(&cb, fd); + int ret = io_submit(ctx, 1, cbs); + + io_destroy(ctx); + return (ret == -EINVAL) ? false : true; +}