Re: [PATCH] dm writecache: SB remove seq_count

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 08/01/2020 19:04, Mikulas Patocka wrote:
BTW. I would be interested if this patch improves performance for you.
Could you test it?

(you also need my previous patch posted here
https://www.redhat.com/archives/dm-devel/2020-January/msg00027.html )

Mikulas




dm-writecache: use REQ_FUA when writing the superblock

When writing the superblock, it may be better to submit just one I/O with
the FUA bit set instead of two I/Os.

Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>

---
  drivers/md/dm-writecache.c |   29 +++++++++++++++--------------
  1 file changed, 15 insertions(+), 14 deletions(-)

Index: linux-2.6/drivers/md/dm-writecache.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-writecache.c	2020-01-08 17:56:41.000000000 +0100
+++ linux-2.6/drivers/md/dm-writecache.c	2020-01-08 17:56:49.000000000 +0100
@@ -448,7 +448,7 @@ static void writecache_wait_for_ios(stru
  		   !atomic_read(&wc->bio_in_progress[direction]));
  }
-static void ssd_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
+static void ssd_commit_flushed(struct dm_writecache *wc, bool wait_for_ios, bool use_fua)
  {
  	struct dm_io_region region;
  	struct dm_io_request req;
@@ -479,7 +479,7 @@ static void ssd_commit_flushed(struct dm
  		region.sector += wc->start_sector;
  		atomic_inc(&endio.count);
  		req.bi_op = REQ_OP_WRITE;
-		req.bi_op_flags = REQ_SYNC;
+		req.bi_op_flags = REQ_SYNC | (use_fua ? REQ_FUA : 0);
  		req.mem.type = DM_IO_VMA;
  		req.mem.ptr.vma = (char *)wc->memory_map + (size_t)i * BITMAP_GRANULARITY;
  		req.client = wc->dm_io;
@@ -497,17 +497,18 @@ static void ssd_commit_flushed(struct dm
  	if (wait_for_ios)
  		writecache_wait_for_ios(wc, WRITE);
- writecache_disk_flush(wc, wc->ssd_dev);
+	if (!use_fua)
+		writecache_disk_flush(wc, wc->ssd_dev);
memset(wc->dirty_bitmap, 0, wc->dirty_bitmap_size);
  }
-static void writecache_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
+static void writecache_commit_flushed(struct dm_writecache *wc, bool wait_for_ios, bool use_fua)
  {
  	if (WC_MODE_PMEM(wc))
  		wmb();
  	else
-		ssd_commit_flushed(wc, wait_for_ios);
+		ssd_commit_flushed(wc, wait_for_ios, use_fua);
  }
static void writecache_disk_flush(struct dm_writecache *wc, struct dm_dev *dev)
@@ -727,12 +728,12 @@ static void writecache_flush(struct dm_w
  		e = e2;
  		cond_resched();
  	}
-	writecache_commit_flushed(wc, true);
+	writecache_commit_flushed(wc, true, false);
wc->seq_count++;
  	pmem_assign(sb(wc)->seq_count, cpu_to_le64(wc->seq_count));
  	writecache_flush_region(wc, &sb(wc)->seq_count, sizeof sb(wc)->seq_count);
-	writecache_commit_flushed(wc, false);
+	writecache_commit_flushed(wc, false, true);
wc->overwrote_committed = false; @@ -756,7 +757,7 @@ static void writecache_flush(struct dm_w
  	}
if (need_flush_after_free)
-		writecache_commit_flushed(wc, false);
+		writecache_commit_flushed(wc, false, false);
  }
static void writecache_flush_work(struct work_struct *work)
@@ -809,7 +810,7 @@ static void writecache_discard(struct dm
  	}
if (discarded_something)
-		writecache_commit_flushed(wc, false);
+		writecache_commit_flushed(wc, false, false);
  }
static bool writecache_wait_for_writeback(struct dm_writecache *wc)
@@ -958,7 +959,7 @@ erase_this:
if (need_flush) {
  		writecache_flush_all_metadata(wc);
-		writecache_commit_flushed(wc, false);
+		writecache_commit_flushed(wc, false, false);
  	}
wc_unlock(wc);
@@ -1342,7 +1343,7 @@ static void __writecache_endio_pmem(stru
  			wc->writeback_size--;
  			n_walked++;
  			if (unlikely(n_walked >= ENDIO_LATENCY)) {
-				writecache_commit_flushed(wc, false);
+				writecache_commit_flushed(wc, false, false);
  				wc_unlock(wc);
  				wc_lock(wc);
  				n_walked = 0;
@@ -1423,7 +1424,7 @@ pop_from_list:
  			writecache_wait_for_ios(wc, READ);
  		}
- writecache_commit_flushed(wc, false);
+		writecache_commit_flushed(wc, false, false);
wc_unlock(wc);
  	}
@@ -1766,10 +1767,10 @@ static int init_memory(struct dm_writeca
  		write_original_sector_seq_count(wc, &wc->entries[b], -1, -1);
writecache_flush_all_metadata(wc);
-	writecache_commit_flushed(wc, false);
+	writecache_commit_flushed(wc, false, false);
  	pmem_assign(sb(wc)->magic, cpu_to_le32(MEMORY_SUPERBLOCK_MAGIC));
  	writecache_flush_region(wc, &sb(wc)->magic, sizeof sb(wc)->magic);
-	writecache_commit_flushed(wc, false);
+	writecache_commit_flushed(wc, false, false);
return 0;
  }


Hi Mikulas

On a test disk, performance is same with or without patch.
Using fio 4k rand write iops:
12 K iops with sync/fua = 0
2.7K iops with sync/fua = 1

------- Without patch ----------

fio --name=4kiops --filename=/dev/vg1/slow --rw=randwrite --bs=4k --direct=1 --sync=0 --runtime=10 --time_based --numjobs=16 --iodepth=1 --group_reporting

Run status group 0 (all jobs):
WRITE: bw=46.9MiB/s (49.2MB/s), 46.9MiB/s-46.9MiB/s (49.2MB/s-49.2MB/s), io=469MiB (492MB), run=10005-10005msec

fio --name=4kiops --filename=/dev/vg1/slow --rw=randwrite --bs=4k --direct=1 --sync=1 --runtime=10 --time_based --numjobs=16 --iodepth=1 --group_reporting

Run status group 0 (all jobs):
WRITE: bw=10.7MiB/s (11.2MB/s), 10.7MiB/s-10.7MiB/s (11.2MB/s-11.2MB/s), io=107MiB (112MB), run=10007-1000 7msec


------- With patch ----------

fio --name=4kiops --filename=/dev/vg1/slow --rw=randwrite --bs=4k --direct=1 --sync=0 --runtime=10 --time_based --numjobs=16 --iodepth=1 --group_reporting

Run status group 0 (all jobs):
WRITE: bw=46.8MiB/s (49.0MB/s), 46.8MiB/s-46.8MiB/s (49.0MB/s-49.0MB/s), io=468MiB (491MB), run=10004-10004msec

fio --name=4kiops --filename=/dev/vg1/slow --rw=randwrite --bs=4k --direct=1 --sync=1 --runtime=10 --time_based --numjobs=16 --iodepth=1 --group_reporting

Run status group 0 (all jobs):
WRITE: bw=10.8MiB/s (11.3MB/s), 10.8MiB/s-10.8MiB/s (11.3MB/s-11.3MB/s), io=108MiB (113MB), run=10005-10005msec

/Maged

--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel




[Index of Archives]     [DM Crypt]     [Fedora Desktop]     [ATA RAID]     [Fedora Marketing]     [Fedora Packaging]     [Fedora SELinux]     [Yosemite Discussion]     [KDE Users]     [Fedora Docs]

  Powered by Linux