[dm-devel] RFC: REQ_PRIO use
Christoph Hellwig
hch at infradead.org
Tue Nov 20 09:39:07 UTC 2018
We have two places that check the flag, the writeback tracking
code:
block/blk-wbt.c:#define REQ_HIPRIO (REQ_SYNC | REQ_META | REQ_PRIO)
block/blk-wbt.c: if ((rw & REQ_HIPRIO) || wb_recent_wait(rwb) || current_is_kswapd())
and bcache:
drivers/md/bcache/request.c: !(bio->bi_opf & REQ_PRIO))
drivers/md/bcache/request.c: !(bio->bi_opf & REQ_PRIO) &&
the original idea was that not all I/O is a priority we should not
blindly boost priority for metadata. Of course wbt actually ignores
and it and we may just give in and just check REQ_META, except for
the fact that f2fs now actually submits REQ_PRIO requests without
REQ_META..
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