Toward non-blocking asynchronous I/O

Posted May 31, 2017 6:07 UTC (Wed) by ringerc (subscriber, #3071)
Parent article: Toward non-blocking asynchronous I/O

Last time I checked it seemed like we couldn't even trust the AIO layer to provide a reliable fsync() for buffered AIO, so it seems like it's pretty useless for anything except O_DIRECT.

Would still be beneficial to have async fsync even with O_DIRECT

Posted May 31, 2017 20:20 UTC (Wed) by sitsofe (guest, #104576) [Link]

O_DIRECT implies that the I/O won't be left rolling around in the OS' cache but says nothing about whether it is still in the disk device's non-volatile cache. You could send all I/Os down with O_SYNC too but speeds will plummet. Thus it's still desirable to be able to send down an fsync (and it would have been preferable if submitting it didn't have to block)...