On 02/26/2017 01:58 PM, Davidlohr Bueso wrote: > On Wed, 22 Feb 2017, Waiman Long wrote: > >> On a 2-socket 36-core 72-thread x86-64 E5-2699 v3 system, a rwsem >> microbenchmark was run with 36 locking threads (one/core) doing 100k >> reader and writer lock/unlock operations each, the resulting locking >> rates (avg of 3 runs) on a 4.10 kernel were 561.4 Mop/s and 588.8 >> Mop/s without and with the patch respectively. That was an increase >> of about 5%. > > iirc this patch is a repost, no? If so, did you get a chance to measure > single file access with direct io as dchinner suggested? > > Thanks, > Davidlohr
Yes, this patch is a derivative of part of the rwsem reader spinning patch set that I posted before. The major change here in this patch is from the unconditional spitting into 2 atomic adds to a conditional spitting depending the on OSQ state and the ability to acquire the wait_lock immediately without waiting. This should reduce the concern that you have with the original patch. I will run a single-file direct I/O test as well. Cheers, Longman
