From: Mikulas Patocka <mpatocka@redhat.com>
To: Mikulas Patocka <mpatocka@redhat.com>,
dm-devel@redhat.com, msnitzer@redhat.com
Subject: [dm-devel] [PATCH 1/1] dm writecache: commit just one block, not a full page
Date: Mon, 21 Jun 2021 20:09:02 +0200 [thread overview]
Message-ID: <20210621180952.629801486@debian3.vm> (raw)
In-Reply-To: 20210621180901.669593725@debian3.vm
Some architectures have pages larger than 4k and committing a full page
causes needless overhead.
Fix this by writing a single block when committing the superblock.
Writes smaller than 4k are slow on most SSDs (because the SSD performs
read-modify-write internally), so make sure that we write at least 4k.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Index: linux-2.6/drivers/md/dm-writecache.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-writecache.c
+++ linux-2.6/drivers/md/dm-writecache.c
@@ -532,7 +532,7 @@ static void ssd_commit_superblock(struct
region.bdev = wc->ssd_dev->bdev;
region.sector = 0;
- region.count = PAGE_SIZE >> SECTOR_SHIFT;
+ region.count = max(4096U, wc->block_size) >> SECTOR_SHIFT;
if (unlikely(region.sector + region.count > wc->metadata_sectors))
region.count = wc->metadata_sectors - region.sector;
--
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prev parent reply other threads:[~2021-06-21 18:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-21 18:09 [dm-devel] [PATCH 0/1] dm writecache: commit just one block, not a full page Mikulas Patocka
2021-06-21 18:09 ` Mikulas Patocka [this message]
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