From e828cccb72ed8661b5d778baae9442cd06da4e0e Mon Sep 17 00:00:00 2001 From: Sergey Senozhatsky Date: Sat, 22 Nov 2025 16:40:25 +0900 Subject: [PATCH] zram: add writeback batch size device attr 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. Link: https://lkml.kernel.org/r/20251122074029.3948921-3-senozhatsky@chromium.org Signed-off-by: Sergey Senozhatsky Reviewed-by: Brian Geffon Cc: Minchan Kim Cc: Richard Chang Cc: Yuwen Chen Signed-off-by: Andrew Morton --- drivers/block/zram/zram_drv.c | 46 ++++++++++++++++++++++++++++++----- drivers/block/zram/zram_drv.h | 1 + 2 files changed, 41 insertions(+), 6 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 06ea56f0a00f6..5906ba0611657 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -590,6 +590,40 @@ static ssize_t writeback_limit_show(struct device *dev, return sysfs_emit(buf, "%llu\n", val); } +static ssize_t writeback_batch_size_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct zram *zram = dev_to_zram(dev); + u32 val; + + if (kstrtouint(buf, 10, &val)) + return -EINVAL; + + if (!val) + return -EINVAL; + + down_write(&zram->init_lock); + zram->wb_batch_size = val; + up_write(&zram->init_lock); + + return len; +} + +static ssize_t writeback_batch_size_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + u32 val; + struct zram *zram = dev_to_zram(dev); + + down_read(&zram->init_lock); + val = 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) @@ -781,10 +815,7 @@ static void release_wb_ctl(struct zram_wb_ctl *wb_ctl) kfree(wb_ctl); } -/* XXX: should be a per-device sysfs attr */ -#define ZRAM_WB_REQ_CNT 32 - -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; @@ -799,7 +830,7 @@ static struct zram_wb_ctl *init_wb_ctl(void) init_waitqueue_head(&wb_ctl->done_wait); spin_lock_init(&wb_ctl->done_lock); - for (i = 0; i < ZRAM_WB_REQ_CNT; i++) { + for (i = 0; i < zram->wb_batch_size; i++) { struct zram_wb_req *req; /* @@ -1200,7 +1231,7 @@ static ssize_t writeback_store(struct device *dev, goto release_init_lock; } - wb_ctl = init_wb_ctl(); + wb_ctl = init_wb_ctl(zram); if (!wb_ctl) { ret = -ENOMEM; goto release_init_lock; @@ -2843,6 +2874,7 @@ 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); @@ -2864,6 +2896,7 @@ static struct attribute *zram_disk_attrs[] = { &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, @@ -2925,6 +2958,7 @@ static int zram_add(void) init_rwsem(&zram->init_lock); #ifdef CONFIG_ZRAM_WRITEBACK + zram->wb_batch_size = 32; spin_lock_init(&zram->wb_limit_lock); #endif diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 6cee93f9c0d06..1a647f42c1a48 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; -- 2.47.3