On 23/08/14 10:22, Somnath Roy wrote:
I think it is using direct io for non-aio mode as well.
Thanks & Regards
Somnath
One thing that does still concern me - if I understand what is happening here correctly: we write to the journal using aio until we want to stop doing writes (presumably pre closing it), then use normal io to write at that point.
Given that we appear to be using direct io whenever we use aio, does this mean we end up mixing direct and buffered io to the journal [1] (or is the normal i.e non aio write still using direct io)?
Thanks Somnath,
I think you are correct (I missed the bit in FileJournal::_open that
seems to cover this):
if (forwrite) {
flags = O_RDWR;
if (directio)
flags |= O_DIRECT | O_DSYNC;
i.e the journal is opened with DIRECT, so all writes (async or not) will
be direct.
Cheers
Mark
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