zram: remove zram->lock in read path and change it with mutex
Finally, we separated zram->lock dependency from 32bit stat/ table handling so there is no reason to use rw_semaphore between read and write path so this patch removes the lock from read path totally and changes rw_semaphore with mutex. So, we could do old: read-read: OK read-write: NO write-write: NO Now: read-read: OK read-write: OK write-write: NO The below data proves mixed workload performs well 11 times and there is also enhance on write-write path because current rw-semaphore doesn't support SPIN_ON_OWNER. It's side effect but anyway good thing for us. Write-related tests perform better (from 61% to 1058%) but read path has good/bad(from -2.22% to 1.45%) but they are all marginal within stddev. CPU 12 iozone -t -T -l 12 -u 12 -r 16K -s 60M -I +Z -V 0 ==Initial write ==Initial write records: 10 records: 10 avg: 516189.16 avg: 839907.96 std: 22486.53 (4.36%) std: 47902.17 (5.70%) max: 546970.60 max: 909910.35 min: 481131.54 min: 751148.38 ==Rewrite ==Rewrite records: 10 records: 10 avg: 509527.98 avg: 1050156.37 std: 45799.94 (8.99%) std: 40695.44 (3.88%) max: 611574.27 max: 1111929.26 min: 443679.95 min: 980409.62 ==Read ==Read records: 10 records: 10 avg: 4408624.17 avg: 4472546.76 std: 281152.61 (6.38%) std: 163662.78 (3.66%) max: 4867888.66 max: 4727351.03 min: 4058347.69 min: 4126520.88 ==Re-read ==Re-read records: 10 records: 10 avg: 4462147.53 avg: 4363257.75 std: 283546.11 (6.35%) std: 247292.63 (5.67%) max: 4912894.44 max: 4677241.75 min: 4131386.50 min: 4035235.84 ==Reverse Read ==Reverse Read records: 10 records: 10 avg: 4565865.97 avg: 4485818.08 std: 313395.63 (6.86%) std: 248470.10 (5.54%) max: 5232749.16 max: 4789749.94 min: 4185809.62 min: 3963081.34 ==Stride read ==Stride read records: 10 records: 10 avg: 4515981.80 avg: 4418806.01 std: 211192.32 (4.68%) std: 212837.97 (4.82%) max: 4889287.28 max: 4686967.22 min: 4210362.00 min: 4083041.84 ==Random read ==Random read records: 10 records: 10 avg: 4410525.23 avg: 4387093.18 std: 236693.22 (5.37%) std: 235285.23 (5.36%) max: 4713698.47 max: 4669760.62 min: 4057163.62 min: 3952002.16 ==Mixed workload ==Mixed workload records: 10 records: 10 avg: 243234.25 avg: 2818677.27 std: 28505.07 (11.72%) std: 195569.70 (6.94%) max: 288905.23 max: 3126478.11 min: 212473.16 min: 2484150.69 ==Random write ==Random write records: 10 records: 10 avg: 555887.07 avg: 1053057.79 std: 70841.98 (12.74%) std: 35195.36 (3.34%) max: 683188.28 max: 1096125.73 min: 437299.57 min: 992481.93 ==Pwrite ==Pwrite records: 10 records: 10 avg: 501745.93 avg: 810363.09 std: 16373.54 (3.26%) std: 19245.01 (2.37%) max: 518724.52 max: 833359.70 min: 464208.73 min: 765501.87 ==Pread ==Pread records: 10 records: 10 avg: 4539894.60 avg: 4457680.58 std: 197094.66 (4.34%) std: 188965.60 (4.24%) max: 4877170.38 max: 4689905.53 min: 4226326.03 min: 4095739.72 Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Nitin Gupta <ngupta@vflare.org> Tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Minchan Kim
Linus Torvalds
Родитель
f614a9f48d
Коммит
e46e33152e
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@ -230,6 +230,7 @@ static struct zram_meta *zram_meta_alloc(u64 disksize)
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}
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rwlock_init(&meta->tb_lock);
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mutex_init(&meta->buffer_lock);
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return meta;
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free_table:
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@ -412,6 +413,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
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struct page *page;
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unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
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struct zram_meta *meta = zram->meta;
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bool locked = false;
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page = bvec->bv_page;
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src = meta->compress_buffer;
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@ -431,6 +433,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
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goto out;
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}
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mutex_lock(&meta->buffer_lock);
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locked = true;
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user_mem = kmap_atomic(page);
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if (is_partial_io(bvec)) {
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@ -457,7 +461,6 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
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ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
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meta->compress_workmem);
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if (!is_partial_io(bvec)) {
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kunmap_atomic(user_mem);
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user_mem = NULL;
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@ -514,6 +517,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
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atomic_inc(&zram->stats.good_compress);
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out:
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if (locked)
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mutex_unlock(&meta->buffer_lock);
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if (is_partial_io(bvec))
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kfree(uncmem);
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@ -527,15 +532,10 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
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{
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int ret;
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if (rw == READ) {
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down_read(&zram->lock);
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if (rw == READ)
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ret = zram_bvec_read(zram, bvec, index, offset, bio);
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up_read(&zram->lock);
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} else {
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down_write(&zram->lock);
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else
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ret = zram_bvec_write(zram, bvec, index, offset);
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up_write(&zram->lock);
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}
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return ret;
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}
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@ -808,7 +808,6 @@ static int create_device(struct zram *zram, int device_id)
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{
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int ret = -ENOMEM;
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init_rwsem(&zram->lock);
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init_rwsem(&zram->init_lock);
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zram->queue = blk_alloc_queue(GFP_KERNEL);
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@ -88,13 +88,11 @@ struct zram_meta {
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void *compress_buffer;
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struct table *table;
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struct zs_pool *mem_pool;
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struct mutex buffer_lock; /* protect compress buffers */
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};
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struct zram {
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struct zram_meta *meta;
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struct rw_semaphore lock; /* protect compression buffers,
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* reads and writes
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*/
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struct request_queue *queue;
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struct gendisk *disk;
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int init_done;
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