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 AAD74C433EF for ; Fri, 8 Jul 2022 04:26:34 +0000 (UTC) Received: from localhost ([::1]:40566 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1o9fZZ-0006Yw-O1 for qemu-devel@archiver.kernel.org; Fri, 08 Jul 2022 00:26:33 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35646) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o9fSy-0003vL-MH for qemu-devel@nongnu.org; Fri, 08 Jul 2022 00:19:45 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:54160) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o9fSw-0000OT-Jc for qemu-devel@nongnu.org; Fri, 08 Jul 2022 00:19:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657253981; 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=JROyeDCuqRPYheOCOIiVjDQFrHQ+HPgpGEYy8Gg1Q3A=; b=CHxf6NC7xm991b+4mujU4xObyMmPfcnqyrIZKX+3gnzBnEl/s20jxJhqzLdd1C5m3+aB4D hwvKyLPDVTawF2EBSoXRAl1yt2TFVBsk9oz6vEhHnTTV2Dl6/hvSgoJHRqkXKZ1imE+mFe uE881BcnExnhRsucI+U58CCL0EN5ZXY= 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-93-YmTOPGAYMb2jdRK9_KjDBA-1; Fri, 08 Jul 2022 00:19:35 -0400 X-MC-Unique: YmTOPGAYMb2jdRK9_KjDBA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id A49603C0E22A; Fri, 8 Jul 2022 04:19:34 +0000 (UTC) Received: from localhost (unknown [10.39.192.20]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3AB48C23DBF; Fri, 8 Jul 2022 04:19:34 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: Alberto Faria , Stefan Hajnoczi , Vladimir Sementsov-Ogievskiy , "Michael S. Tsirkin" , Paolo Bonzini , Laurent Vivier , Eric Blake , sgarzare@redhat.com, Marcel Apfelbaum , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , qemu-block@nongnu.org, Eduardo Habkost , Vladimir Sementsov-Ogievskiy , John Snow , Thomas Huth , Kevin Wolf , Markus Armbruster , Hanna Reitz , Fam Zheng , Yanan Wang Subject: [RFC v3 7/8] blkio: implement BDRV_REQ_REGISTERED_BUF optimization Date: Fri, 8 Jul 2022 05:17:36 +0100 Message-Id: <20220708041737.1768521-8-stefanha@redhat.com> In-Reply-To: <20220708041737.1768521-1-stefanha@redhat.com> References: <20220708041737.1768521-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.85 on 10.11.54.8 Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable 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" Avoid bounce buffers when QEMUIOVector elements are within previously registered bdrv_register_buf() buffers. The idea is that emulated storage controllers will register guest RAM using bdrv_register_buf() and set the BDRV_REQ_REGISTERED_BUF on I/O requests. Therefore no blkio_map_mem_region() calls are necessary in the performance-critical I/O code path. This optimization doesn't apply if the I/O buffer is internally allocated by QEMU (e.g. qcow2 metadata). There we still take the slow path because BDRV_REQ_REGISTERED_BUF is not set. Signed-off-by: Stefan Hajnoczi --- block/blkio.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 101 insertions(+), 3 deletions(-) diff --git a/block/blkio.c b/block/blkio.c index 7fbdbd7fae..37d593a20c 100644 --- a/block/blkio.c +++ b/block/blkio.c @@ -1,7 +1,9 @@ #include "qemu/osdep.h" #include #include "block/block_int.h" +#include "exec/memory.h" #include "qapi/error.h" +#include "qemu/error-report.h" #include "qapi/qmp/qdict.h" #include "qemu/module.h" @@ -28,6 +30,9 @@ typedef struct { /* Can we skip adding/deleting blkio_mem_regions? */ bool needs_mem_regions; + + /* Are file descriptors necessary for blkio_mem_regions? */ + bool needs_mem_region_fd; } BDRVBlkioState; static void blkio_aiocb_complete(BlkioAIOCB *acb, int ret) @@ -198,6 +203,8 @@ static BlockAIOCB *blkio_aio_preadv(BlockDriverState *bs, int64_t offset, BlockCompletionFunc *cb, void *opaque) { BDRVBlkioState *s = bs->opaque; + bool needs_mem_regions = + s->needs_mem_regions && !(flags & BDRV_REQ_REGISTERED_BUF); struct iovec *iov = qiov->iov; int iovcnt = qiov->niov; BlkioAIOCB *acb; @@ -206,7 +213,7 @@ static BlockAIOCB *blkio_aio_preadv(BlockDriverState *bs, int64_t offset, acb = blkio_aiocb_get(bs, cb, opaque); - if (s->needs_mem_regions) { + if (needs_mem_regions) { if (blkio_aiocb_init_mem_region_locked(acb, bytes) < 0) { qemu_aio_unref(&acb->common); return NULL; @@ -230,6 +237,8 @@ static BlockAIOCB *blkio_aio_pwritev(BlockDriverState *bs, int64_t offset, { uint32_t blkio_flags = (flags & BDRV_REQ_FUA) ? BLKIO_REQ_FUA : 0; BDRVBlkioState *s = bs->opaque; + bool needs_mem_regions = + s->needs_mem_regions && !(flags & BDRV_REQ_REGISTERED_BUF); struct iovec *iov = qiov->iov; int iovcnt = qiov->niov; BlkioAIOCB *acb; @@ -238,7 +247,7 @@ static BlockAIOCB *blkio_aio_pwritev(BlockDriverState *bs, int64_t offset, acb = blkio_aiocb_get(bs, cb, opaque); - if (s->needs_mem_regions) { + if (needs_mem_regions) { if (blkio_aiocb_init_mem_region_locked(acb, bytes) < 0) { qemu_aio_unref(&acb->common); return NULL; @@ -324,6 +333,80 @@ static void blkio_io_unplug(BlockDriverState *bs) } } +static void blkio_register_buf(BlockDriverState *bs, void *host, size_t size) +{ + BDRVBlkioState *s = bs->opaque; + int ret; + struct blkio_mem_region region = (struct blkio_mem_region){ + .addr = host, + .len = size, + .fd = -1, + }; + + if (((uintptr_t)host | size) % s->mem_region_alignment) { + error_report_once("%s: skipping unaligned buf %p with size %zu", + __func__, host, size); + return; /* skip unaligned */ + } + + /* Attempt to find the fd for a MemoryRegion */ + if (s->needs_mem_region_fd) { + int fd = -1; + ram_addr_t offset; + MemoryRegion *mr; + + /* + * bdrv_register_buf() is called with the BQL held so mr lives at least + * until this function returns. + */ + mr = memory_region_from_host(host, &offset); + if (mr) { + fd = memory_region_get_fd(mr); + } + if (fd == -1) { + error_report_once("%s: skipping fd-less buf %p with size %zu", + __func__, host, size); + return; /* skip if there is no fd */ + } + + region.fd = fd; + region.fd_offset = offset; + } + + WITH_QEMU_LOCK_GUARD(&s->lock) { + ret = blkio_map_mem_region(s->blkio, ®ion); + } + + if (ret < 0) { + error_report_once("Failed to add blkio mem region %p with size %zu: %s", + host, size, blkio_get_error_msg()); + } +} + +static void blkio_unregister_buf(BlockDriverState *bs, void *host, size_t size) +{ + BDRVBlkioState *s = bs->opaque; + int ret; + struct blkio_mem_region region = (struct blkio_mem_region){ + .addr = host, + .len = size, + .fd = -1, + }; + + if (((uintptr_t)host | size) % s->mem_region_alignment) { + return; /* skip unaligned */ + } + + WITH_QEMU_LOCK_GUARD(&s->lock) { + ret = blkio_unmap_mem_region(s->blkio, ®ion); + } + + if (ret < 0) { + error_report_once("Failed to delete blkio mem region %p with size %zu: %s", + host, size, blkio_get_error_msg()); + } +} + static void blkio_parse_filename_io_uring(const char *filename, QDict *options, Error **errp) { @@ -440,6 +523,17 @@ static int blkio_file_open(BlockDriverState *bs, QDict *options, int flags, return ret; } + ret = blkio_get_bool(s->blkio, + "needs-mem-region-fd", + &s->needs_mem_region_fd); + if (ret < 0) { + error_setg_errno(errp, -ret, + "failed to get needs-mem-region-fd: %s", + blkio_get_error_msg()); + blkio_destroy(&s->blkio); + return ret; + } + ret = blkio_get_uint64(s->blkio, "mem-region-alignment", &s->mem_region_alignment); @@ -459,7 +553,7 @@ static int blkio_file_open(BlockDriverState *bs, QDict *options, int flags, return ret; } - bs->supported_write_flags = BDRV_REQ_FUA; + bs->supported_write_flags = BDRV_REQ_FUA | BDRV_REQ_REGISTERED_BUF; bs->supported_zero_flags = BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK; @@ -627,6 +721,8 @@ static BlockDriver bdrv_io_uring = { .bdrv_co_pwrite_zeroes = blkio_co_pwrite_zeroes, .bdrv_io_unplug = blkio_io_unplug, .bdrv_refresh_limits = blkio_refresh_limits, + .bdrv_register_buf = blkio_register_buf, + .bdrv_unregister_buf = blkio_unregister_buf, }; static BlockDriver bdrv_virtio_blk_vhost_vdpa = { @@ -648,6 +744,8 @@ static BlockDriver bdrv_virtio_blk_vhost_vdpa = { .bdrv_co_pwrite_zeroes = blkio_co_pwrite_zeroes, .bdrv_io_unplug = blkio_io_unplug, .bdrv_refresh_limits = blkio_refresh_limits, + .bdrv_register_buf = blkio_register_buf, + .bdrv_unregister_buf = blkio_unregister_buf, }; static void bdrv_blkio_init(void) -- 2.36.1