On Tue, 2022-02-22 at 15:00 +0100, Philippe Schenker wrote: > On Tue, 2022-02-22 at 08:41 +0900, Damien Le Moal wrote: > > On 2/21/22 23:40, Philippe Schenker wrote: > > > Hello > > > > > > We use FIO to check the eMMC storage on our embedded boards. This > > > works > > > great for our modules that have >= 1GB RAM but on all lower-memory > > > ones > > > (<= 512MB) the OOM killer always kills FIO. > > > > > > I can hook up a swap which helps but is just painfully slow. > > > > Well yes, your system will be trashing... > > > > > > > > I played with the settings mem, bs, iodepth and size but cannot > > > achieve > > > a configuration that works on low-memory embedded systems. > > > > > > Can anyone guide me how I can make this work? > > > > See if playing with option "--alloc-size=" helps. You can also > > reduce > > the maximum number of jobs with "--max-jobs=". Also try using > > threads > > instead of (default) processes for jobs (--thread option). And of > > course > > make sure that the total amount of IO buffers you need (num jobs * > > io > > depth per job * bs) is not too large for your RAM size. > > Thank you very much for your help on this topic. I tried those > parameters back and forth, however it seems to always reserve ~400MB > on > the biggest chunk (checked in /proc/<pid-of-fio>/smaps). > > decreasing the max allowed shared memory in /proc/sys/kernel/shmmax to > ~64M does solve our issue and fio works also on 256MB ram. > > However this leads to the question if this is not a bug? I mean it > seems > to reserve this memory despite it's not needing it? > What leads me to this assumption is that I can also set mem=malloc > instead of mem=shm and I get still the same error. > > We use fio 3.17 is this maybe solved in newer versions? I built fio 3.29 in the meantime and tried it with that and oh wonder I have absolutely no issues, so it seems I hit an old bug. Sorry for the noise and thanks again Damien for your kind help! Philippe > > Best Regards, > Philippe > > > > > > > > > Best Regards, > > > Philippe > > > > > > > >
