On Wed, May 08 2019 at 12:46pm -0400, Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > > > On Tue, 7 May 2019, Mike Snitzer wrote: > > > On Mon, Apr 29 2019 at 8:57am -0400, > > Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > > > > > Add a new bitmap mode for dm-integrity. > > > > > > Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> > > > > This patch header needs much more detail. > > > > Can you please be as informative and detailed as possible about what > > this new bitmap mode is (what constraints it has, where it is expected > > to be useful, etc)? Also, if you have them, provide some benchmarks > > that showcase its benefits. > > > > Thanks, > > Mike > > The patch adds the documentation to the file > "Documentation/device-mapper/dm-integrity.txt", so it can be also used as > a patch header. For example: > > "This patch introduces an alternative mode of operation whete dm-integrity > uses bitmap instead of a journal. If a bit in the bitmap is 1, the > corresponding region's data and integrity tags are not synchronized - if > the machine crashes, the unsynchronized regions will be recalculated. The > bitmap mode is faster than the journal mode, because we don't have to > write the data twice, but it is also less reliable, because if data > corruption happens when the machine crashes, it may not be detected." > > Benchmark - on an SSD connected to a SATA300 port, when doing large linear > writes with dd. > > buffered I/O: > raw device throughput - 245MB/s > dm-integrity with journaling - 120MB/s > dm-integrity with bitmap - 238MB/s > > direct I/O with 1MB block size: > raw device throughput - 248MB/s > dm-integrity with journaling - 123MB/s > dm-integrity with bitmap - 223MB/s Great, thanks. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
