Il giorno gio, 28/11/2019 alle 17.17 +0800, Ming Lei ha scritto: > On Thu, Nov 28, 2019 at 08:46:57AM +0100, Andrea Vai wrote: > > Il giorno mer, 27/11/2019 alle 08.14 +0000, Schmid, Carsten ha > > scritto: > > > > > > > > > Then I started another set of 100 trials and let them run > > > tonight, and > > > > > the first 10 trials were around 1000s, then gradually > decreased > > > to > > > > > ~300s, and finally settled around 200s with some trials > below > > > 70-80s. > > > > > This to say, times are extremely variable and for the first > time > > > I > > > > > noticed a sort of "performance increase" with time. > > > > > > > > > > > > > The sheer volume of testing (probably some terabytes by now) > would > > > > exercise the wear leveling algorithm in the FTL. > > > > > > > But with "old kernel" the copy operation still is "fast", as far > as > > > i understood. > > > If FTL (e.g. wear leveling) would slow down, we would see that > also > > > in > > > the old kernel, right? > > > > > > Andrea, can you confirm that the same device used with the old > fast > > > kernel is still fast today? > > > > Yes, it is still fast. Just ran a 100 trials test and got an > average > > of 70 seconds with standard deviation = 6 seconds, aligned with > the > > past values of the same kernel. > > Then can you collect trace on the old kernel via the previous > script? > > #!/bin/sh > > MAJ=$1 > MIN=$2 > MAJ=$(( $MAJ << 20 )) > DEV=$(( $MAJ | $MIN )) > > /usr/share/bcc/tools/trace -t -C \ > 't:block:block_rq_issue (args->dev == '$DEV') "%s %d %d", args- > >rwbs, args->sector, args->nr_sector' \ > 't:block:block_rq_insert (args->dev == '$DEV') "%s %d %d", args- > >rwbs, args->sector, args->nr_sector' > > Both the two trace points and bcc should be available on the old > kernel. > Trace attached. Produced by: start the trace script (with the pendrive already plugged), wait some seconds, run the test (1 trial, 1 GB), wait for the test to finish, stop the trace. The copy took 73 seconds, roughly as already seen before with the fast old kernel. Thanks, Andrea
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