On 7/31/20 8:28 AM, Pavel Begunkov wrote: > On 30/07/2020 21:08, Jens Axboe wrote: >> On 7/30/20 9:43 AM, Pavel Begunkov wrote: >>> [1/1] takes apart the union, too much trouble and there is no reason >>> left for keeping it. Probably for 5.10 we can reshuffle the layout as >>> discussed. >> >> Let's hope so, because I do think this is the safest option, but it does >> incur a 5% drop for me. > > Hmm, any ideas why? If your test doesn't use neither apoll/poll/io-wq, > then it looks like either something related to slab (e.g. partial zeroing), > or magic with @task_work moved from 4th to 3rd cacheline. Was looking into it just now, but I think it was just a bad test run. Checked out and ran a new test, and then just with #1 applied which would be the only one that should impact things. And it's pretty close, so I'm going to call it a wash. So nothing to worry about I think. -- Jens Axboe
