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AJvYcCXtsP1KsZ04YeCz3rQ67Jrg8FRI7UB7O89v1cXSmpishCaD6KSfdENB8zOQXosKYew3nZEn1wuj4C0=@vger.kernel.org X-Gm-Message-State: AOJu0YzV5bOOZTB+MtHzRKgaICPf+tspFjJdmpqKa+WtdmdJm6JSs/cq YN2H6LnIcF0LOuHg7c0UNN72gHF4QwjMzLe1CzZU7eIN5eZ96xI2kFH0hMOPi0SiVhb1hC3e2JL qoScg2Abdjoaprm0MaHgP49eDrei+L1I= X-Gm-Gg: ASbGncsErOElAqPmrL0Nn83nQgb5uzpJRHWiFNEfLDFYWcdlj56KHsC3me6TESHdjye 1zM0uhJY3kLsXJPwuoKPsEIh01IAqLdGSHxLdrr+tUhvAdFrhNCjFgDOeKRmiOoSctNIye4INGI lQ+xF6Jc/KbW+KNxBXvn86z1tsiiPsmbvDVnU9OmAaKVFznu4qAwN2U3LOQoUYO0IqpBQeVZk+N H7n2xFxUelt91hdT29WDlaD/Jlzsu7Y X-Google-Smtp-Source: AGHT+IE7mG3LNkxY+CyodDwm/x4ptJOMQVJ+H4EmrH8p/RVIObpZc3vVfG1SaOV6rlrj3vGwgT1jiZxnhaAD3dJIuBQ= X-Received: by 2002:a05:6102:6cf:b0:524:b344:748d with SMTP id ada2fe7eead31-5d5e23474fcmr5780092137.17.1760147041875; Fri, 10 Oct 2025 18:44:01 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20251011013312.20698-1-changfengnan@bytedance.com> In-Reply-To: From: fengnan chang Date: Sat, 11 Oct 2025 09:43:51 +0800 X-Gm-Features: AS18NWCBO3jy7FdLyGcQVogGXlatyQB1qaqtXtY1KzxOp2alt1gh71U3rIH7rWo Message-ID: Subject: Re: [PATCH] block: enable per-cpu bio cache by default To: Fengnan Chang , linux-block@vger.kernel.org Cc: axboe@kernel.dk, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, asml.silence@gmail.com, willy@infradead.org, djwong@kernel.org, hch@infradead.org, ritesh.list@gmail.com, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable cc more maillist On Sat, Oct 11, 2025 at 9:36=E2=80=AFAM fengnan chang wrote: > > The attachment is result of fio test ext4/xfs with > libaio/sync/io_uring on null_blk and > nvme. > > On Sat, Oct 11, 2025 at 9:33=E2=80=AFAM Fengnan Chang > wrote: > > > > Per cpu bio cache was only used in the io_uring + raw block device, > > after commit 12e4e8c7ab59 ("io_uring/rw: enable bio caches for IRQ > > rw"), bio_put is safe for task and irq context, bio_alloc_bioset is > > safe for task context and no one calls in irq context, so we can enable > > per cpu bio cache by default. > > > > Benchmarked with t/io_uring and ext4+nvme: > > taskset -c 6 /root/fio/t/io_uring -p0 -d128 -b4096 -s1 -c1 -F1 -B1 -R1 > > -X1 -n1 -P1 /mnt/testfile > > base IOPS is 562K, patch IOPS is 574K. The CPU usage of bio_alloc_biose= t > > decrease from 1.42% to 1.22%. > > > > The worst case is allocate bio in CPU A but free in CPU B, still use > > t/io_uring and ext4+nvme: > > base IOPS is 648K, patch IOPS is 647K. > > > > Also use fio test ext4/xfs with libaio/sync/io_uring on null_blk and > > nvme, no obvious performance regression. > > > > Signed-off-by: Fengnan Chang > > --- > > block/bio.c | 26 ++++++++++++-------------- > > block/blk-map.c | 4 ++++ > > block/fops.c | 4 ---- > > include/linux/fs.h | 3 --- > > io_uring/rw.c | 1 - > > 5 files changed, 16 insertions(+), 22 deletions(-) > > > > diff --git a/block/bio.c b/block/bio.c > > index 3b371a5da159..16b20c10cab7 100644 > > --- a/block/bio.c > > +++ b/block/bio.c > > @@ -513,20 +513,18 @@ struct bio *bio_alloc_bioset(struct block_device = *bdev, unsigned short nr_vecs, > > if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) && nr_vec= s > 0)) > > return NULL; > > > > - if (opf & REQ_ALLOC_CACHE) { > > - if (bs->cache && nr_vecs <=3D BIO_INLINE_VECS) { > > - bio =3D bio_alloc_percpu_cache(bdev, nr_vecs, o= pf, > > - gfp_mask, bs); > > - if (bio) > > - return bio; > > - /* > > - * No cached bio available, bio returned below = marked with > > - * REQ_ALLOC_CACHE to particpate in per-cpu all= oc cache. > > - */ > > - } else { > > - opf &=3D ~REQ_ALLOC_CACHE; > > - } > > - } > > + opf |=3D REQ_ALLOC_CACHE; > > + if (bs->cache && nr_vecs <=3D BIO_INLINE_VECS) { > > + bio =3D bio_alloc_percpu_cache(bdev, nr_vecs, opf, > > + gfp_mask, bs); > > + if (bio) > > + return bio; > > + /* > > + * No cached bio available, bio returned below marked w= ith > > + * REQ_ALLOC_CACHE to participate in per-cpu alloc cach= e. > > + */ > > + } else > > + opf &=3D ~REQ_ALLOC_CACHE; > > > > /* > > * submit_bio_noacct() converts recursion to iteration; this me= ans if > > diff --git a/block/blk-map.c b/block/blk-map.c > > index 23e5d5ebe59e..570a7ca6edd1 100644 > > --- a/block/blk-map.c > > +++ b/block/blk-map.c > > @@ -255,6 +255,10 @@ static struct bio *blk_rq_map_bio_alloc(struct req= uest *rq, > > { > > struct bio *bio; > > > > + /* > > + * Even REQ_ALLOC_CACHE is enabled by default, we still need th= is to > > + * mark bio is allocated by bio_alloc_bioset. > > + */ > > if (rq->cmd_flags & REQ_ALLOC_CACHE && (nr_vecs <=3D BIO_INLINE= _VECS)) { > > bio =3D bio_alloc_bioset(NULL, nr_vecs, rq->cmd_flags, = gfp_mask, > > &fs_bio_set); > > diff --git a/block/fops.c b/block/fops.c > > index ddbc69c0922b..090562a91b4c 100644 > > --- a/block/fops.c > > +++ b/block/fops.c > > @@ -177,8 +177,6 @@ static ssize_t __blkdev_direct_IO(struct kiocb *ioc= b, struct iov_iter *iter, > > loff_t pos =3D iocb->ki_pos; > > int ret =3D 0; > > > > - if (iocb->ki_flags & IOCB_ALLOC_CACHE) > > - opf |=3D REQ_ALLOC_CACHE; > > bio =3D bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL, > > &blkdev_dio_pool); > > dio =3D container_of(bio, struct blkdev_dio, bio); > > @@ -326,8 +324,6 @@ static ssize_t __blkdev_direct_IO_async(struct kioc= b *iocb, > > loff_t pos =3D iocb->ki_pos; > > int ret =3D 0; > > > > - if (iocb->ki_flags & IOCB_ALLOC_CACHE) > > - opf |=3D REQ_ALLOC_CACHE; > > bio =3D bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL, > > &blkdev_dio_pool); > > dio =3D container_of(bio, struct blkdev_dio, bio); > > diff --git a/include/linux/fs.h b/include/linux/fs.h > > index 601d036a6c78..18ec41732186 100644 > > --- a/include/linux/fs.h > > +++ b/include/linux/fs.h > > @@ -365,8 +365,6 @@ struct readahead_control; > > /* iocb->ki_waitq is valid */ > > #define IOCB_WAITQ (1 << 19) > > #define IOCB_NOIO (1 << 20) > > -/* can use bio alloc cache */ > > -#define IOCB_ALLOC_CACHE (1 << 21) > > /* > > * IOCB_DIO_CALLER_COMP can be set by the iocb owner, to indicate that= the > > * iocb completion can be passed back to the owner for execution from = a safe > > @@ -399,7 +397,6 @@ struct readahead_control; > > { IOCB_WRITE, "WRITE" }, \ > > { IOCB_WAITQ, "WAITQ" }, \ > > { IOCB_NOIO, "NOIO" }, \ > > - { IOCB_ALLOC_CACHE, "ALLOC_CACHE" }, \ > > { IOCB_DIO_CALLER_COMP, "CALLER_COMP" }, \ > > { IOCB_AIO_RW, "AIO_RW" }, \ > > { IOCB_HAS_METADATA, "AIO_HAS_METADATA" } > > diff --git a/io_uring/rw.c b/io_uring/rw.c > > index af5a54b5db12..fa7655ab9097 100644 > > --- a/io_uring/rw.c > > +++ b/io_uring/rw.c > > @@ -856,7 +856,6 @@ static int io_rw_init_file(struct io_kiocb *req, fm= ode_t mode, int rw_type) > > ret =3D kiocb_set_rw_flags(kiocb, rw->flags, rw_type); > > if (unlikely(ret)) > > return ret; > > - kiocb->ki_flags |=3D IOCB_ALLOC_CACHE; > > > > /* > > * If the file is marked O_NONBLOCK, still allow retry for it i= f it > > -- > > 2.39.5 (Apple Git-154) > > > >