On Wed, Mar 24, 2021 at 09:44:21AM -0400, Josef Bacik wrote: > Looking at perf data for a fio workload I noticed that we were spending > a pretty large chunk of time (around 5%) doing percpu_counter_sum() in > need_preemptive_reclaim. This is silly, as we only want to know if we > have more ordered than delalloc to see if we should be counting the > delayed items in our threshold calculation. Change this to > percpu_read_positive() to avoid the overhead. > > I ran this through fsperf to validate the changes, obviously the latency > numbers in dbench and fio are quite jittery, so take them as you wish, > but overall the improvements on throughput, iops, and bw are all > positive. Each test was run two times, the given value is the average > of both runs for their respective column. > > btrfs ssd normal test results > > bufferedrandwrite16g results > metric baseline current diff > ========================================================== > write_io_kbytes 16777216 16777216 0.00% > read_clat_ns_p99 0 0 0.00% > write_bw_bytes 1.04e+08 1.05e+08 1.12% > read_iops 0 0 0.00% > write_clat_ns_p50 13888 11840 -14.75% > read_io_kbytes 0 0 0.00% > read_io_bytes 0 0 0.00% > write_clat_ns_p99 35008 29312 -16.27% > read_bw_bytes 0 0 0.00% > elapsed 170 167 -1.76% > write_lat_ns_min 4221.50 3762.50 -10.87% > sys_cpu 39.65 35.37 -10.79% > write_lat_ns_max 2.67e+10 2.50e+10 -6.63% > read_lat_ns_min 0 0 0.00% > write_iops 25270.10 25553.43 1.12% > read_lat_ns_max 0 0 0.00% > read_clat_ns_p50 0 0 0.00% > > dbench60 results > metric baseline current diff > ================================================== > qpathinfo 11.12 12.73 14.52% > throughput 416.09 445.66 7.11% > flush 3485.63 1887.55 -45.85% > qfileinfo 0.70 1.92 173.86% > ntcreatex 992.60 695.76 -29.91% > qfsinfo 2.43 3.71 52.48% > close 1.67 3.14 88.09% > sfileinfo 66.54 105.20 58.10% > rename 809.23 619.59 -23.43% > find 16.88 15.46 -8.41% > unlink 820.54 670.86 -18.24% > writex 3375.20 2637.91 -21.84% > deltree 386.33 449.98 16.48% > readx 3.43 3.41 -0.60% > mkdir 0.05 0.03 -38.46% > lockx 0.26 0.26 -0.76% > unlockx 0.81 0.32 -60.33% > > dio4kbs16threads results > metric baseline current diff > ================================================================ > write_io_kbytes 5249676 3357150 -36.05% > read_clat_ns_p99 0 0 0.00% > write_bw_bytes 89583501.50 57291192.50 -36.05% > read_iops 0 0 0.00% > write_clat_ns_p50 242688 263680 8.65% > read_io_kbytes 0 0 0.00% > read_io_bytes 0 0 0.00% > write_clat_ns_p99 15826944 36732928 132.09% > read_bw_bytes 0 0 0.00% > elapsed 61 61 0.00% > write_lat_ns_min 42704 42095 -1.43% > sys_cpu 5.27 3.45 -34.52% > write_lat_ns_max 7.43e+08 9.27e+08 24.71% > read_lat_ns_min 0 0 0.00% > write_iops 21870.97 13987.11 -36.05% > read_lat_ns_max 0 0 0.00% > read_clat_ns_p50 0 0 0.00% > > randwrite2xram results > metric baseline current diff > ================================================================ > write_io_kbytes 24831972 28876262 16.29% > read_clat_ns_p99 0 0 0.00% > write_bw_bytes 83745273.50 92182192.50 10.07% > read_iops 0 0 0.00% > write_clat_ns_p50 13952 11648 -16.51% > read_io_kbytes 0 0 0.00% > read_io_bytes 0 0 0.00% > write_clat_ns_p99 50176 52992 5.61% > read_bw_bytes 0 0 0.00% > elapsed 314 332 5.73% > write_lat_ns_min 5920.50 5127 -13.40% > sys_cpu 7.82 7.35 -6.07% > write_lat_ns_max 5.27e+10 3.88e+10 -26.44% > read_lat_ns_min 0 0 0.00% > write_iops 20445.62 22505.42 10.07% > read_lat_ns_max 0 0 0.00% > read_clat_ns_p50 0 0 0.00% > > untarfirefox results > metric baseline current diff > ============================================== > elapsed 47.41 47.40 -0.03% > > Signed-off-by: Josef Bacik <jo...@toxicpanda.com>
Added to misc-next, thanks.
