On 4/28/20 6:55 PM, Jens Axboe wrote: > On 4/28/20 5:41 PM, Eric Sandeen wrote: >> This seems ... large, no? >> >> # /usr/bin/time -f "RSS %M kb" ./fio --name=writetest --filename=/mnt/testfile1 --rw=write --bs=4096 --size=64M --iodepth=1 --ioengine=libaio --direct=1 --verify=sha512 --do_verify=0 >> >> RSS 1138748 kb >> >> and it got quite a bit larger with commit >> >> df8781b6 fio: groundwork for adding slat, lat percentiles >> >> i.e. if I check out the commit just before that, >> >> ab45cf07 Merge branch 'stat-averaging-interval-start-fix' of https://github.com/maciejsszmigiero/fio >> >> I get: >> >> RSS 782236 kb >> >> which is, if I'm reading it right, ~350mb smaller. >> >> 760mb seems pretty big for a simple fio job like this in the first >> place, that commit growing it by 350mb is unexpected and I ... haven't >> been able to figure out where that increase came from. Am I >> mis-analyzing something here? > > It probably got larger with that commit because it added to the > thread_data, and fio defaults to a large number of jobs... You can try > and add: > > --max-jobs=X > > to shrink the max jobs it supports, that'll reduce it drastically. I > think we default to 4k of jobs by default, or something like that, and > each job will consume ~274K. Ah, that's what I was missing. That commit grew an array by 3x but I couldn't get from there to 350MB. It's obvious now, thanks! Not sure how I missed that. OTOH, 4k default seems like a lot of overhead... -Eric
