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Thu, 13 Nov 2025 00:54:26 -0800 (PST) Received: from tigerii.tok.corp.google.com ([2401:fa00:8f:203:6d96:d8c6:55e6:2377]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2985c2346f3sm17486465ad.18.2025.11.13.00.54.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Nov 2025 00:54:25 -0800 (PST) From: Sergey Senozhatsky To: Andrew Morton , Minchan Kim , Yuwen Chen , Richard Chang Cc: Brian Geffon , Fengyu Lian , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, Sergey Senozhatsky Subject: [PATCHv2 2/4] zram: add writeback batch size device attr Date: Thu, 13 Nov 2025 17:54:00 +0900 Message-ID: <20251113085402.1811522-3-senozhatsky@chromium.org> X-Mailer: git-send-email 2.51.2.1041.gc1ab5b90ca-goog In-Reply-To: <20251113085402.1811522-1-senozhatsky@chromium.org> References: <20251113085402.1811522-1-senozhatsky@chromium.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Introduce writeback_batch_size device attribute so that the maximum number of in-flight writeback bio requests can be configured at run-time per-device. This essentially enables batched bio writeback. Signed-off-by: Sergey Senozhatsky --- drivers/block/zram/zram_drv.c | 48 ++++++++++++++++++++++++++++++----- drivers/block/zram/zram_drv.h | 1 + 2 files changed, 43 insertions(+), 6 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index a0a939fd9d31..238b997f6891 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -570,6 +570,42 @@ static ssize_t writeback_limit_show(struct device *dev, return sysfs_emit(buf, "%llu\n", val); } =20 +static ssize_t writeback_batch_size_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct zram *zram =3D dev_to_zram(dev); + u32 val; + ssize_t ret =3D -EINVAL; + + if (kstrtouint(buf, 10, &val)) + return ret; + + if (!val) + val =3D 1; + + down_read(&zram->init_lock); + zram->wb_batch_size =3D val; + up_read(&zram->init_lock); + ret =3D len; + + return ret; +} + +static ssize_t writeback_batch_size_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + u32 val; + struct zram *zram =3D dev_to_zram(dev); + + down_read(&zram->init_lock); + val =3D zram->wb_batch_size; + up_read(&zram->init_lock); + + return sysfs_emit(buf, "%u\n", val); +} + static void reset_bdev(struct zram *zram) { if (!zram->backing_dev) @@ -776,10 +812,7 @@ static void release_wb_ctl(struct zram_wb_ctl *wb_ctl) kfree(wb_ctl); } =20 -/* XXX: should be a per-device sysfs attr */ -#define ZRAM_WB_REQ_CNT 1 - -static struct zram_wb_ctl *init_wb_ctl(void) +static struct zram_wb_ctl *init_wb_ctl(struct zram *zram) { struct zram_wb_ctl *wb_ctl; int i; @@ -793,7 +826,7 @@ static struct zram_wb_ctl *init_wb_ctl(void) atomic_set(&wb_ctl->num_inflight, 0); init_completion(&wb_ctl->done); =20 - for (i =3D 0; i < ZRAM_WB_REQ_CNT; i++) { + for (i =3D 0; i < zram->wb_batch_size; i++) { struct zram_wb_req *req; =20 /* @@ -1182,7 +1215,7 @@ static ssize_t writeback_store(struct device *dev, goto release_init_lock; } =20 - wb_ctl =3D init_wb_ctl(); + wb_ctl =3D init_wb_ctl(zram); if (!wb_ctl) { ret =3D -ENOMEM; goto release_init_lock; @@ -2823,6 +2856,7 @@ static DEVICE_ATTR_RW(backing_dev); static DEVICE_ATTR_WO(writeback); static DEVICE_ATTR_RW(writeback_limit); static DEVICE_ATTR_RW(writeback_limit_enable); +static DEVICE_ATTR_RW(writeback_batch_size); #endif #ifdef CONFIG_ZRAM_MULTI_COMP static DEVICE_ATTR_RW(recomp_algorithm); @@ -2844,6 +2878,7 @@ static struct attribute *zram_disk_attrs[] =3D { &dev_attr_writeback.attr, &dev_attr_writeback_limit.attr, &dev_attr_writeback_limit_enable.attr, + &dev_attr_writeback_batch_size.attr, #endif &dev_attr_io_stat.attr, &dev_attr_mm_stat.attr, @@ -2905,6 +2940,7 @@ static int zram_add(void) =20 init_rwsem(&zram->init_lock); #ifdef CONFIG_ZRAM_WRITEBACK + zram->wb_batch_size =3D 1; spin_lock_init(&zram->wb_limit_lock); #endif =20 diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 6cee93f9c0d0..1a647f42c1a4 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -129,6 +129,7 @@ struct zram { struct file *backing_dev; spinlock_t wb_limit_lock; bool wb_limit_enable; + u32 wb_batch_size; u64 bd_wb_limit; struct block_device *bdev; unsigned long *bitmap; --=20 2.51.2.1041.gc1ab5b90ca-goog