On Tue, Mar 31, 2020 at 7:31 PM David Howells <dhowells@xxxxxxxxxx> wrote: > > Miklos Szeredi <miklos@xxxxxxxxxx> wrote: > > > The basic problem in my view, is that the performance requirement of a > > "get filesystem information" type of API just does not warrant a > > binary coded interface. I've said this a number of times, but it fell > > on deaf ears. > > It hasn't so fallen, but don't necessarily agree with you. Let's pin some > numbers on this. Cool, thanks for testing. Unfortunately the test-fsinfo-perf.c file didn't make it into the patch. Can you please refresh and resend? > Okay, the results: > > For 1000 mounts, f= 1514us f2= 1102us p= 6014us p2= 6935us; p=4.0*f p=5.5*f2 p=0.9*p2 > For 2000 mounts, f= 4712us f2= 3675us p= 20937us p2= 22878us; p=4.4*f p=5.7*f2 p=0.9*p2 > For 3000 mounts, f= 6795us f2= 5304us p= 31080us p2= 34056us; p=4.6*f p=5.9*f2 p=0.9*p2 > For 4000 mounts, f= 9291us f2= 7434us p= 40723us p2= 46479us; p=4.4*f p=5.5*f2 p=0.9*p2 > For 5000 mounts, f=11423us f2= 9219us p= 50878us p2= 58857us; p=4.5*f p=5.5*f2 p=0.9*p2 > For 10000 mounts, f=22899us f2=18240us p=101054us p2=117273us; p=4.4*f p=5.5*f2 p=0.9*p2 > For 20000 mounts, f=45811us f2=37211us p=203640us p2=237377us; p=4.4*f p=5.5*f2 p=0.9*p2 > For 30000 mounts, f=69703us f2=54800us p=306778us p2=357629us; p=4.4*f p=5.6*f2 p=0.9*p2 So even the p2 method will give at least 80k queries/s, which is quite good, considering that the need to rescan the complete mount tree should be exceedingly rare (and in case it mattered, could be optimized by priming from /proc/self/mountinfo). Thanks, Miklos
