On Mon, Mar 11, 2024 at 01:21:32PM +0000, Peter Hruška wrote: > We encountered a problem with performance of writes on GPFS when the > application uses direct io access. To simulate the issue it is enough to run > fio with option direct=1. The performance drop is quite dramatic - 250 MiB/s > vs. 2955 MiB/s. We've tried to instruct GPFS to ignore direct IO by using > "disableDIO=yes". The directive didn't have any effect. Is there any > possibility how to achieve that GPFS would ignore direct IO requests and use > caching for everything?
Hello, did you use pre-allocated file(s) (was it re-write) ? libaio traffic is not really asynchronous with respect to necessary metadata operations (allocating new space and writing allocation structures to disk) in most Linux filesystems and I guess this case is not heavily optimized in GPFS either (dioSmallSeqWriteBatching feature may help a little but it targets different scenario I think). Best regards, Zdenek Salvet sal...@ics.muni.cz Institute of Computer Science of Masaryk University, Brno, Czech Republic and CESNET, z.s.p.o., Prague, Czech Republic Phone: ++420-549 49 6534 Fax: ++420-541 212 747 ---------------------------------------------------------------------------- Teamwork is essential -- it allows you to blame someone else. _______________________________________________ gpfsug-discuss mailing list gpfsug-discuss at gpfsug.org http://gpfsug.org/mailman/listinfo/gpfsug-discuss_gpfsug.org