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This leverages the infrastructure added in the previous commit to handle the completion of I/O operations in a dedicated kthread. This change shows 27% speed improvement of idle writeback on Android platform. Test Flow: - mkfs on the zram device, mount it - cp three linux-6.16-rc2.tar.gz tarball files as the data - do idle writeback - check bd_stat writes 185072 pages Test Result: idle writeback for 185072 4k-pages (~723 MiB) $ echo all > /sys/block/zram0/idle $ time echo idle > /sys/block/zram0/writeback Async writeback: 0m02.49s real 0m00.00s user 0m01.19s system 0m02.32s real 0m00.00s user 0m00.89s system 0m02.35s real 0m00.00s user 0m00.93s system 0m02.29s real 0m00.00s user 0m00.88s system Sync writeback: 0m03.09s real 0m00.00s user 0m01.07s system 0m03.18s real 0m00.00s user 0m01.12s system 0m03.47s real 0m00.00s user 0m01.16s system 0m03.36s real 0m00.00s user 0m01.27s system Signed-off-by: Richard Chang --- drivers/block/zram/zram_drv.c | 109 ++++++++++++++-------------------- drivers/block/zram/zram_drv.h | 11 ++++ drivers/block/zram/zram_wb.c | 103 +++++++++++++++++++++++++++++++- drivers/block/zram/zram_wb.h | 6 +- 4 files changed, 161 insertions(+), 68 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 6098c0bb773c..f459d889fa44 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -57,7 +57,6 @@ static size_t huge_class_size; =20 static const struct block_device_operations zram_devops; =20 -static void zram_free_page(struct zram *zram, size_t index); static int zram_read_from_zspool(struct zram *zram, struct page *page, u32 index); =20 @@ -96,7 +95,7 @@ static __must_check bool zram_slot_trylock(struct zram *z= ram, u32 index) return false; } =20 -static void zram_slot_lock(struct zram *zram, u32 index) +void zram_slot_lock(struct zram *zram, u32 index) { unsigned long *lock =3D &zram->table[index].flags; =20 @@ -105,7 +104,7 @@ static void zram_slot_lock(struct zram *zram, u32 index) lock_acquired(slot_dep_map(zram, index), _RET_IP_); } =20 -static void zram_slot_unlock(struct zram *zram, u32 index) +void zram_slot_unlock(struct zram *zram, u32 index) { unsigned long *lock =3D &zram->table[index].flags; =20 @@ -128,19 +127,17 @@ static unsigned long zram_get_handle(struct zram *zra= m, u32 index) return zram->table[index].handle; } =20 -static void zram_set_handle(struct zram *zram, u32 index, unsigned long ha= ndle) +void zram_set_handle(struct zram *zram, u32 index, unsigned long handle) { zram->table[index].handle =3D handle; } =20 -static bool zram_test_flag(struct zram *zram, u32 index, - enum zram_pageflags flag) +bool zram_test_flag(struct zram *zram, u32 index, enum zram_pageflags flag) { return zram->table[index].flags & BIT(flag); } =20 -static void zram_set_flag(struct zram *zram, u32 index, - enum zram_pageflags flag) +void zram_set_flag(struct zram *zram, u32 index, enum zram_pageflags flag) { zram->table[index].flags |=3D BIT(flag); } @@ -243,15 +240,20 @@ static struct zram_pp_ctl *init_pp_ctl(void) if (!ctl) return NULL; =20 + init_completion(&ctl->all_done); + atomic_set(&ctl->num_pp_slots, 0); for (idx =3D 0; idx < NUM_PP_BUCKETS; idx++) INIT_LIST_HEAD(&ctl->pp_buckets[idx]); return ctl; } =20 -static void release_pp_slot(struct zram *zram, struct zram_pp_slot *pps) +static void remove_pp_slot_from_ctl(struct zram_pp_slot *pps) { list_del_init(&pps->entry); +} =20 +void free_pp_slot(struct zram *zram, struct zram_pp_slot *pps) +{ zram_slot_lock(zram, pps->index); zram_clear_flag(zram, pps->index, ZRAM_PP_SLOT); zram_slot_unlock(zram, pps->index); @@ -259,6 +261,12 @@ static void release_pp_slot(struct zram *zram, struct = zram_pp_slot *pps) kfree(pps); } =20 +static void release_pp_slot(struct zram *zram, struct zram_pp_slot *pps) +{ + remove_pp_slot_from_ctl(pps); + free_pp_slot(zram, pps); +} + static void release_pp_ctl(struct zram *zram, struct zram_pp_ctl *ctl) { u32 idx; @@ -297,6 +305,7 @@ static bool place_pp_slot(struct zram *zram, struct zra= m_pp_ctl *ctl, list_add(&pps->entry, &ctl->pp_buckets[bid]); =20 zram_set_flag(zram, pps->index, ZRAM_PP_SLOT); + atomic_inc(&ctl->num_pp_slots); return true; } =20 @@ -697,18 +706,18 @@ static void read_from_bdev_async(struct zram *zram, s= truct page *page, static int zram_writeback_slots(struct zram *zram, struct zram_pp_ctl *ctl) { unsigned long blk_idx =3D 0; - struct page *page =3D NULL; struct zram_pp_slot *pps; - struct bio_vec bio_vec; - struct bio bio; - int ret =3D 0, err; + int ret =3D 0; u32 index; + int nr_pps =3D atomic_read(&ctl->num_pp_slots); =20 - page =3D alloc_page(GFP_KERNEL); - if (!page) - return -ENOMEM; + if (!nr_pps) + return 0; =20 while ((pps =3D select_pp_slot(ctl))) { + struct zram_wb_request *req; + struct page *page; + spin_lock(&zram->wb_limit_lock); if (zram->wb_limit_enable && !zram->bd_wb_limit) { spin_unlock(&zram->wb_limit_lock); @@ -725,6 +734,13 @@ static int zram_writeback_slots(struct zram *zram, str= uct zram_pp_ctl *ctl) } } =20 + req =3D alloc_wb_request(zram, pps, ctl, blk_idx); + if (IS_ERR(req)) { + ret =3D PTR_ERR(req); + break; + } + page =3D bio_first_page_all(req->bio); + index =3D pps->index; zram_slot_lock(zram, index); /* @@ -739,63 +755,28 @@ static int zram_writeback_slots(struct zram *zram, st= ruct zram_pp_ctl *ctl) goto next; zram_slot_unlock(zram, index); =20 - bio_init(&bio, zram->bdev, &bio_vec, 1, - REQ_OP_WRITE | REQ_SYNC); - bio.bi_iter.bi_sector =3D blk_idx * (PAGE_SIZE >> 9); - __bio_add_page(&bio, page, PAGE_SIZE, 0); - - /* - * XXX: A single page IO would be inefficient for write - * but it would be not bad as starter. - */ - err =3D submit_bio_wait(&bio); - if (err) { - release_pp_slot(zram, pps); - /* - * BIO errors are not fatal, we continue and simply - * attempt to writeback the remaining objects (pages). - * At the same time we need to signal user-space that - * some writes (at least one, but also could be all of - * them) were not successful and we do so by returning - * the most recent BIO error. - */ - ret =3D err; - continue; - } - - atomic64_inc(&zram->stats.bd_writes); - zram_slot_lock(zram, index); - /* - * Same as above, we release slot lock during writeback so - * slot can change under us: slot_free() or slot_free() and - * reallocation (zram_write_page()). In both cases slot loses - * ZRAM_PP_SLOT flag. No concurrent post-processing can set - * ZRAM_PP_SLOT on such slots until current post-processing - * finishes. - */ - if (!zram_test_flag(zram, index, ZRAM_PP_SLOT)) - goto next; - - zram_free_page(zram, index); - zram_set_flag(zram, index, ZRAM_WB); - zram_set_handle(zram, index, blk_idx); + nr_pps--; + remove_pp_slot_from_ctl(pps); blk_idx =3D 0; - atomic64_inc(&zram->stats.pages_stored); - spin_lock(&zram->wb_limit_lock); - if (zram->wb_limit_enable && zram->bd_wb_limit > 0) - zram->bd_wb_limit -=3D 1UL << (PAGE_SHIFT - 12); - spin_unlock(&zram->wb_limit_lock); + submit_bio(req->bio); + continue; + next: zram_slot_unlock(zram, index); release_pp_slot(zram, pps); + free_wb_request(req); =20 cond_resched(); } =20 if (blk_idx) free_block_bdev(zram, blk_idx); - if (page) - __free_page(page); + + if (nr_pps && atomic_sub_and_test(nr_pps, &ctl->num_pp_slots)) + complete(&ctl->all_done); + + /* wait until all async bios completed */ + wait_for_completion(&ctl->all_done); =20 return ret; } @@ -1579,7 +1560,7 @@ static bool zram_meta_alloc(struct zram *zram, u64 di= sksize) return true; } =20 -static void zram_free_page(struct zram *zram, size_t index) +void zram_free_page(struct zram *zram, size_t index) { unsigned long handle; =20 diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 2c7bc05fb186..ab5ceecc8ed8 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -140,6 +140,13 @@ struct zram { atomic_t pp_in_progress; }; =20 +void zram_slot_lock(struct zram *zram, u32 index); +void zram_slot_unlock(struct zram *zram, u32 index); +void zram_set_handle(struct zram *zram, u32 index, unsigned long handle); +bool zram_test_flag(struct zram *zram, u32 index, enum zram_pageflags flag= ); +void zram_set_flag(struct zram *zram, u32 index, enum zram_pageflags flag); +void zram_free_page(struct zram *zram, size_t index); + #if defined CONFIG_ZRAM_WRITEBACK || defined CONFIG_ZRAM_MULTI_COMP struct zram_pp_slot { unsigned long index; @@ -155,7 +162,11 @@ struct zram_pp_slot { =20 struct zram_pp_ctl { struct list_head pp_buckets[NUM_PP_BUCKETS]; + struct completion all_done; + atomic_t num_pp_slots; }; + +void free_pp_slot(struct zram *zram, struct zram_pp_slot *pps); #endif =20 #endif diff --git a/drivers/block/zram/zram_wb.c b/drivers/block/zram/zram_wb.c index 63a16dae5796..3b8edd048dcb 100644 --- a/drivers/block/zram/zram_wb.c +++ b/drivers/block/zram/zram_wb.c @@ -43,15 +43,60 @@ void free_block_bdev(struct zram *zram, unsigned long b= lk_idx) static void complete_wb_request(struct zram_wb_request *req) { struct zram *zram =3D req->zram; + struct zram_pp_slot *pps =3D req->pps; + struct zram_pp_ctl *ctl =3D req->ppctl; + unsigned long index =3D pps->index; unsigned long blk_idx =3D req->blk_idx; + struct bio *bio =3D req->bio; + + if (bio->bi_status) + goto out_err; + + atomic64_inc(&zram->stats.bd_writes); + zram_slot_lock(zram, index); + + /* + * We release slot lock during writeback so slot can change + * under us: slot_free() or slot_free() and reallocation + * (zram_write_page()). In both cases slot loses + * ZRAM_PP_SLOT flag. No concurrent post-processing can set + * ZRAM_PP_SLOT on such slots until current post-processing + * finishes. + */ + if (!zram_test_flag(zram, index, ZRAM_PP_SLOT)) { + zram_slot_unlock(zram, index); + goto out_err; + } =20 + zram_free_page(zram, index); + zram_set_flag(zram, index, ZRAM_WB); + zram_set_handle(zram, index, blk_idx); + atomic64_inc(&zram->stats.pages_stored); + spin_lock(&zram->wb_limit_lock); + if (zram->wb_limit_enable && zram->bd_wb_limit > 0) + zram->bd_wb_limit -=3D 1UL << (PAGE_SHIFT - 12); + spin_unlock(&zram->wb_limit_lock); + zram_slot_unlock(zram, index); + goto end; + +out_err: free_block_bdev(zram, blk_idx); +end: + free_pp_slot(zram, pps); free_wb_request(req); + + if (atomic_dec_and_test(&ctl->num_pp_slots)) + complete(&ctl->all_done); } =20 -void enqueue_wb_request(struct zram_wb_request_list *req_list, - struct zram_wb_request *req) +static void enqueue_wb_request(struct zram_wb_request_list *req_list, + struct zram_wb_request *req) { + /* + * The enqueue path comes from softirq context: + * blk_done_softirq -> bio_endio -> zram_writeback_end_io + * Use spin_lock_bh for locking. + */ spin_lock_bh(&req_list->lock); list_add_tail(&req->node, &req_list->head); req_list->count++; @@ -83,6 +128,7 @@ static void destroy_wb_request_list(struct zram_wb_reque= st_list *req_list) while (!list_empty(&req_list->head)) { req =3D dequeue_wb_request(req_list); free_block_bdev(req->zram, req->blk_idx); + free_pp_slot(req->zram, req->pps); free_wb_request(req); } } @@ -117,6 +163,59 @@ static int wb_thread_func(void *data) return 0; } =20 +static void zram_writeback_end_io(struct bio *bio) +{ + struct zram_wb_request *req =3D + (struct zram_wb_request *)bio->bi_private; + + enqueue_wb_request(&wb_req_list, req); + wake_up(&wb_wq); +} + +struct zram_wb_request *alloc_wb_request(struct zram *zram, + struct zram_pp_slot *pps, + struct zram_pp_ctl *ppctl, + unsigned long blk_idx) +{ + struct zram_wb_request *req; + struct page *page; + struct bio *bio; + int err =3D 0; + + page =3D alloc_page(GFP_NOIO | __GFP_NOWARN); + if (!page) + return ERR_PTR(-ENOMEM); + + bio =3D bio_alloc(zram->bdev, 1, REQ_OP_WRITE, GFP_NOIO | __GFP_NOWARN); + if (!bio) { + err =3D -ENOMEM; + goto out_free_page; + } + + req =3D kmalloc(sizeof(struct zram_wb_request), GFP_NOIO | __GFP_NOWARN); + if (!req) { + err =3D -ENOMEM; + goto out_free_bio; + } + req->zram =3D zram; + req->pps =3D pps; + req->ppctl =3D ppctl; + req->blk_idx =3D blk_idx; + req->bio =3D bio; + + bio->bi_iter.bi_sector =3D blk_idx * (PAGE_SIZE >> 9); + __bio_add_page(bio, page, PAGE_SIZE, 0); + bio->bi_private =3D req; + bio->bi_end_io =3D zram_writeback_end_io; + return req; + +out_free_bio: + bio_put(bio); +out_free_page: + __free_page(page); + return ERR_PTR(err); +} + void free_wb_request(struct zram_wb_request *req) { struct bio *bio =3D req->bio; diff --git a/drivers/block/zram/zram_wb.h b/drivers/block/zram/zram_wb.h index b86de0398346..f6fe7c51d496 100644 --- a/drivers/block/zram/zram_wb.h +++ b/drivers/block/zram/zram_wb.h @@ -26,9 +26,11 @@ unsigned long alloc_block_bdev(struct zram *zram); void free_block_bdev(struct zram *zram, unsigned long blk_idx); int setup_zram_writeback(void); void destroy_zram_writeback(void); +struct zram_wb_request *alloc_wb_request(struct zram *zram, + struct zram_pp_slot *pps, + struct zram_pp_ctl *ppctl, + unsigned long blk_idx); void free_wb_request(struct zram_wb_request *req); -void enqueue_wb_request(struct zram_wb_request_list *req_list, - struct zram_wb_request *req); #else inline unsigned long alloc_block_bdev(struct zram *zram) { return 0; } inline void free_block_bdev(struct zram *zram, unsigned long blk_idx) {}; --=20 2.50.1.565.gc32cd1483b-goog