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 4FA77C433EF for ; Wed, 30 Mar 2022 10:58:05 +0000 (UTC) Received: from localhost ([::1]:43412 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nZW1c-0005w9-CT for qemu-devel@archiver.kernel.org; Wed, 30 Mar 2022 06:58:04 -0400 Received: from eggs.gnu.org ([209.51.188.92]:50346) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nZVpM-00050u-T4 for qemu-devel@nongnu.org; Wed, 30 Mar 2022 06:45:24 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:31677) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nZVpJ-0002kE-7B for qemu-devel@nongnu.org; Wed, 30 Mar 2022 06:45:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1648637119; 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=uAnz5OTL9afX2H2UeXd4pQEKcfRf/sqQKmVXQRRgLA0=; b=iulbP7oIVrRJAgf2iCMwqGAiqKDKzz1qRw2DKRBgk4SoPiS1WVp59OYYWLHZ1ZPXqfPI3K RFp0hl8tqmHnlxB+sMf6FBv3ekTKk8zwq7iegeF7sZiOKchQRWUbgfnl5zIN8EC2x5j6jC 6E/4Zp4pJ8OCLzVl1wMXARc/pRLlnWs= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-613-WpC07N9fM66NrVdCOBJTrA-1; Wed, 30 Mar 2022 06:45:14 -0400 X-MC-Unique: WpC07N9fM66NrVdCOBJTrA-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 162EE811E76; Wed, 30 Mar 2022 10:45:14 +0000 (UTC) Received: from localhost (unknown [10.39.195.140]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1CF66C202C8; Wed, 30 Mar 2022 10:45:12 +0000 (UTC) Date: Wed, 30 Mar 2022 11:45:12 +0100 From: Stefan Hajnoczi To: Stefano Garzarella Subject: Re: [RFC 7/8] blkio: implement BDRV_REQ_REGISTERED_BUF optimization Message-ID: References: <20220323111727.1100209-1-stefanha@redhat.com> <20220323111727.1100209-8-stefanha@redhat.com> <20220329152430.xhmhiq2l2cibzoio@sgarzare-redhat> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="NcGqCjzGynsaE5GW" Content-Disposition: inline In-Reply-To: <20220329152430.xhmhiq2l2cibzoio@sgarzare-redhat> 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, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Cc: Laurent Vivier , Kevin Wolf , Thomas Huth , Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, "Michael S. Tsirkin" , John Snow , qemu-devel@nongnu.org, Alberto Faria , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , Yanan Wang , Eduardo Habkost , Hanna Reitz , Paolo Bonzini , Fam Zheng , Eric Blake , Markus Armbruster Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --NcGqCjzGynsaE5GW Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Mar 29, 2022 at 05:24:30PM +0200, Stefano Garzarella wrote: > On Wed, Mar 23, 2022 at 11:17:26AM +0000, Stefan Hajnoczi wrote: > > Avoid bounce buffers when QEMUIOVector elements are within previously > > registered bdrv_register_buf() buffers. > >=20 > > 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_add_mem_region() calls are necessary in the > > performance-critical I/O code path. > >=20 > > 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. > >=20 > > Signed-off-by: Stefan Hajnoczi > > --- > > block/blkio.c | 108 ++++++++++++++++++++++++++++++++++++++++++++++++-- > > 1 file changed, 104 insertions(+), 4 deletions(-) > >=20 > > diff --git a/block/blkio.c b/block/blkio.c > > index dd2308b967..78f4ca5f49 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" > >=20 > > @@ -26,6 +28,9 @@ typedef struct { > > /* Can we skip adding/deleting blkio_mem_regions? */ > > bool needs_mem_regions; > >=20 > > + /* Are file descriptors necessary for blkio_mem_regions? */ > > + bool needs_mem_region_fd; > > + > > /* > > * blkio_completion_fd_poll() stashes the next completion for > > * blkio_completion_fd_poll_ready(). > > @@ -170,6 +175,8 @@ static BlockAIOCB *blkio_aio_preadv(BlockDriverStat= e *bs, int64_t offset, > > BlockCompletionFunc *cb, void *opaque) > > { > > BDRVBlkioState *s =3D bs->opaque; > > + bool needs_mem_regions =3D > > + s->needs_mem_regions && !(flags & BDRV_REQ_REGISTERED_BUF); > > struct iovec *iov =3D qiov->iov; > > int iovcnt =3D qiov->niov; > > BlkioAIOCB *acb; > > @@ -179,7 +186,7 @@ static BlockAIOCB *blkio_aio_preadv(BlockDriverStat= e *bs, int64_t offset, > >=20 > > acb =3D blkio_aiocb_get(bs, cb, opaque); > >=20 > > - 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; > > @@ -194,7 +201,7 @@ static BlockAIOCB *blkio_aio_preadv(BlockDriverStat= e *bs, int64_t offset, > >=20 > > ret =3D blkioq_readv(s->blkioq, offset, iov, iovcnt, acb, 0); > > if (ret < 0) { > > - if (s->needs_mem_regions) { > > + if (needs_mem_regions) { > > blkio_free_mem_region(s->blkio, &acb->mem_region); > > qemu_iovec_destroy(&acb->qiov); > > } > > @@ -215,6 +222,8 @@ static BlockAIOCB *blkio_aio_pwritev(BlockDriverSta= te *bs, int64_t offset, > > { > > uint32_t blkio_flags =3D (flags & BDRV_REQ_FUA) ? BLKIO_REQ_FUA : 0; > > BDRVBlkioState *s =3D bs->opaque; > > + bool needs_mem_regions =3D > > + s->needs_mem_regions && !(flags & BDRV_REQ_REGISTERED_BUF); > > struct iovec *iov =3D qiov->iov; > > int iovcnt =3D qiov->niov; > > BlkioAIOCB *acb; > > @@ -224,7 +233,7 @@ static BlockAIOCB *blkio_aio_pwritev(BlockDriverSta= te *bs, int64_t offset, > >=20 > > acb =3D blkio_aiocb_get(bs, cb, opaque); > >=20 > > - 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; > > @@ -238,7 +247,7 @@ static BlockAIOCB *blkio_aio_pwritev(BlockDriverSta= te *bs, int64_t offset, > >=20 > > ret =3D blkioq_writev(s->blkioq, offset, iov, iovcnt, acb, blkio_fl= ags); > > if (ret < 0) { > > - if (s->needs_mem_regions) { > > + if (needs_mem_regions) { > > blkio_free_mem_region(s->blkio, &acb->mem_region); > > } > > qemu_aio_unref(&acb->common); > > @@ -286,6 +295,83 @@ static void blkio_io_unplug(BlockDriverState *bs) > > } > > } > >=20 > > +static void blkio_register_buf(BlockDriverState *bs, void *host, size_= t size) > > +{ > > + BDRVBlkioState *s =3D bs->opaque; > > + char *errmsg; > > + int ret; > > + struct blkio_mem_region region =3D (struct blkio_mem_region){ > > + .addr =3D host, > > + .len =3D size, > > + .fd =3D -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 =3D -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 =3D memory_region_from_host(host, &offset); > > + if (mr) { > > + fd =3D memory_region_get_fd(mr); > > + } > > + if (fd =3D=3D -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 =3D fd; > > + region.fd_offset =3D offset; > > + } > > + > > + WITH_QEMU_LOCK_GUARD(&s->lock) { > > + ret =3D blkio_add_mem_region(s->blkio, ®ion, &errmsg); > > + } > > + > > + if (ret < 0) { > > + error_report_once("Failed to add blkio mem region %p with size= %zu: %s", > > + host, size, errmsg); > > + free(errmsg); > > + } > > +} > > + > > +static void blkio_unregister_buf(BlockDriverState *bs, void *host, siz= e_t size) > > +{ > > + BDRVBlkioState *s =3D bs->opaque; > > + char *errmsg; > > + int ret; > > + struct blkio_mem_region region =3D (struct blkio_mem_region){ > > + .addr =3D host, > > + .len =3D size, > > + }; > > + > > + if (((uintptr_t)host | size) % s->mem_region_alignment) { > > + return; /* skip unaligned */ > > + } > > + > > + WITH_QEMU_LOCK_GUARD(&s->lock) { > > + ret =3D blkio_del_mem_region(s->blkio, ®ion, &errmsg); > > + } > > + > > + if (ret < 0) { > > + error_report_once("Failed to delete blkio mem region %p with s= ize %zu: %s", > > + host, size, errmsg); > > + free(errmsg); > > + } > > +} > > + > > static void blkio_parse_filename_io_uring(const char *filename, QDict *= options, > > Error **errp) > > { > > @@ -356,6 +442,18 @@ static int blkio_file_open(BlockDriverState *bs, Q= Dict *options, int flags, > > return ret; > > } > >=20 > > + ret =3D blkio_get_bool(s->blkio, > > + "needs-mem-region-fd", > > + &s->needs_mem_region_fd, > > + &errmsg); > > + if (ret < 0) { > > + error_setg_errno(errp, -ret, > > + "failed to get needs-mem-region-fd: %s", errm= sg); > > + free(errmsg); > > + blkio_destroy(&s->blkio); > > + return ret; > > + } > > + > > ret =3D blkio_get_uint64(s->blkio, > > "mem-region-alignment", > > &s->mem_region_alignment, >=20 > I already mentioned on IRC while testing the series, but I'm writing it h= ere > so we don't forget ;-) >=20 > To prevent bdrv_driver_pwritev() from removing the BDRV_REQ_REGISTERED_BUF > flag from requests, we should add this: >=20 > @@ -474,7 +474,7 @@ static int blkio_file_open(BlockDriverState *bs, QDic= t *options, int flags, > return ret; > } >=20 > - bs->supported_write_flags =3D BDRV_REQ_FUA; > + bs->supported_write_flags =3D BDRV_REQ_FUA | BDRV_REQ_REGISTERED_BUF; >=20 > qemu_mutex_init(&s->lock); > s->blkioq =3D blkio_get_queue(s->blkio, 0); Thanks, will fix. 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