On Tue, 3 Sep 2013, Andi Kleen wrote: > On Tue, Sep 03, 2013 at 03:06:03PM -0400, Mikulas Patocka wrote: > > Hi Andi > > > > You wrote the original dm-crypt paralllelization patch (commit > > c029772125594e31eb1a5ad9e0913724ed9891f2). This patch improves > > parallelization, it makes data being encrypted on the same CPU that > > submitted the request. > > The motivation for my patches was to make large systems with many > cores scale. > > I think the motivation for yours is to make small systems without > hardware crypto offload slightly faster. > > That's fine (although I suspect it's more and more obscure), as long as > you don't impact the large systems scalability. > > Can you do some tests with a larger system with very parallel IO > (many CPUs submitting) and see if the IO rate is equivalent? > > If that's given the patches are ok for me. > > -Andi The patches mainly help with sequential I/O (sequential I/O is normally submitted from a few CPUs, so existing dm-crypt doesn't parallelize right). There is a decrease of performance when 12 threads are doing writes on ramdisk: Sequential read of two SCSI disks in RAID-0 (throughput): raw read rate: 262MB/s stdev 2.9 existing dm-crypt: 111MB/s stdev 19.4 (it varies greatly) new dm-crypt: 254MB/s stdev 1.5 Sequential read of ramdisk (throughput): raw read rate: 908MB/s stdev 7.7 existing dm-crypt: 133MB/s stdev 0.8 my new dm-crypt: 475MB/s stdev 6 fio --rw=randread --bs=4k --direct=1 Random read (4k block) on ramdisk from 12 threads (time in seconds): raw device: 2.32s stdev 0.02 existing dm-crypt: 17.95s stdev 3.40 new dm-crypt: 15.72s stdev 1.86 fio --rw=randwrite --bs=4k --direct=1 Random write (4k block) on ramdisk from 12 threads (time in seconds): raw device 3.91s stdev 0.01 existing dm-crypt: 21.16s stdev 3.67 new dm-crypt: 27.42s stdev 0.27 fio --rw=randrw --bs=4k --direct=1 Random read+write (4k block) on ramdisk from 12 threads (time in seconds): raw device: 3.09s stdev 0.01 existing dm-crypt: 20.08s stdev 3.48 new dm-crypt: 24.78s stdev 0.13 Tests were done on two six-core Istanbul-class Opterons. I don't have a computer with AES-NI, so I can't test that. Mikulas -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
