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. > > > > Anyways, cya, I'm unsubscribed. > > > > Mike >
