On 27/04/2021 10:52, Ming Lei wrote:
Then you just waste lots of memory, I remember that scsi request payload
is a bit big.
It's true that we waste much memory for regular static requests for when
using hostwide tags today.
One problem in trying to use a single set of "hostwide" static requests is
that we call blk_mq_init_request(..., hctx_idx, ...) ->
set->ops->init_request(.., hctx_idx, ...) for each static rq, and this would
not work for a single set of "hostwide" requests.
And I see a similar problem for a "request queue-wide" sched static
requests.
Maybe we can improve this in future.
OK, fair enough.
JFYI, I am working on this now.
My idea is to introduce a hostwide and request-wide static requests (for
hostwide tagset), and have the per-hctx tags point at them, so that we
don't need to allocate per-hctx static requests.
SCSI init_request callback just ignores hctx_idx passed, so then we can
just call init_request(hctx_idx = 0) for those hostwide/request
queue-wide static requests.
Thanks,
John
