On Fri, Aug 07, 2020 at 11:41:09AM -0700, Hugh Dickins wrote: > My home testing was, effectively, on top of c6fe44d96fc1 (v5.8 plus > your two patches): I did not have in the io_uring changes from the > current tree. In glancing there, I noticed one new and one previous > instance of SetPageWaiters() *after* __add_wait_queue_entry_tail(): > are those correct?
By the way, don't do any performance testing on current Linus tree. This commit: commit 37f4a24c2469a10a4c16c641671bd766e276cf9f (refs/bisect/bad) Author: Ming Lei <ming....@redhat.com> Date: Tue Jun 30 22:03:57 2020 +0800 blk-mq: centralise related handling into blk_mq_get_driver_tag Move .nr_active update and request assignment into blk_mq_get_driver_tag(), all are good to do during getting driver tag. Meantime blk-flush related code is simplified and flush request needn't to update the request table manually any more. Signed-off-by: Ming Lei <ming....@redhat.com> Cc: Christoph Hellwig <h...@infradead.org> Signed-off-by: Jens Axboe <ax...@kernel.dk> slows everything down, at least on my test qemu system. Seems like it's losing block queue tags.