On 2017/10/1 上午6:49, Michael Lyle wrote: > One final attempt to resend, because gmail has been giving me trouble > sending plain text mail. > > Two instances of this. Tested as above, with a big set of random I/Os > that ultimately cover every block in a file (e.g. allowing sequential > writeback). > > With the 5 patches, samsung 940 SSD cache + crummy 5400 RPM USB hard drive: > > Typical seconds look like: > > Reading 38232K from cache in 4809 IO. 38232/4809=7.95k per cache device IO. > > Writing 38112k to cache in 400 I/O = 95.28k -- or we are combining > about 11.9 extents to a contiguous writeback. Tracing, there are > still contiguous things that are not getting merged well, but it's OK. > (I'm hoping plugging makes this better). > > sda 4809.00 38232.00 446.00 38232 446 > sdb 400.00 0.00 38112.00 0 38112 > > Without the 5 patches, a typical second-- > > sda 2509.00 19968.00 316.00 19968 316 > sdb 502.00 0.00 19648.00 0 38112 > > or we are combining about 4.9 extents to a contiguous writeback, and > writing back at about half the rate. All of these numbers are +/- 10% > and obtained by eyeballing and grabbing representative seconds. > > Mike > > On Sat, Sep 30, 2017 at 2:02 AM, Michael Lyle <mlyle@xxxxxxxx> wrote: >> >> Resent because I can't seem to get gmail to not send HTML mail. And off to sleep. >> >> >> On Sat, Sep 30, 2017 at 1:57 AM, Michael Lyle <mlyle@xxxxxxxx> wrote: >>> Two instances of this. >>> >>> With the 5 patches, samsung 940 SSD cache + crummy 5400 RPM USB hard drive: >>> >>> Typical seconds look like: >>> >>> Reading 38232K from cache in 4809 IO. 38232/4809=7.95k per cache device IO. >>> >>> Writing 38112k to cache in 400 I/O = 95.28k -- or we are combining about >>> 11.9 extents to a contiguous writeback. Tracing, there are still contiguous >>> things that are not getting merged well, but it's OK. (I'm hoping plugging >>> makes this better). >>> >>> sda 4809.00 38232.00 446.00 38232 446 >>> sdb 400.00 0.00 38112.00 0 38112 >>> >>> Without the 5 patches, a typical second-- >>> >>> sda 2509.00 19968.00 316.00 19968 316 >>> sdb 502.00 0.00 19648.00 0 38112 >>> >>> or we are combining about 4.9 extents to a contiguous writeback, and writing >>> back at about half the rate. Hi Mike, Get it. Now I am testing your patches (all 5 patches). It has been 12+ hours, should be 12+ hours more. The backing device is a raid0 composed by 4x1.8T 2.5inch harddisk, cache device is a 3.8T NVMe SSD. Block size is 512K. Hope it works as you expected on my server. -- Coly Li
