Stefan Hajnoczi wrote: > Thanks Christoph. > > Cached getlength with pread/pwrite: > % time seconds usecs/call calls errors syscall > ------ ----------- ----------- --------- --------- ---------------- > 96.97 1.760111 11893 148 4 futex > 1.61 0.029209 1 46891 2217 select > 0.28 0.005047 0 64609 timer_gettime > 0.22 0.004059 0 42745 2578 rt_sigreturn > 0.22 0.003911 0 46261 timer_settime > 0.18 0.003280 1093 3 shmdt > 0.17 0.003095 0 23859 pread <--- > 0.17 0.003061 0 42800 write > 0.16 0.002916 0 47759 5151 read > 0.02 0.000285 0 645 writev > [...] > 0.00 0.000000 0 13 lseek > > Note that this is a Tiny Core Linux boot from disk and shutdown; not > very I/O intensive since it only loads a kernel and ~10 MB initramfs > without touching the disk much after kernel load.
Nice. Will give this a try tomorrow with "a bit" more load. We already played with a hack to completely remove the checks from AIO requests, thus avoiding lseek this way - effect as desired, but fragile of course. Jan
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