On Thu, Aug 03, 2017 at 01:35:29AM +0000, Bart Van Assche wrote: > On Wed, 2017-08-02 at 11:31 +0800, Ming Lei wrote: > > On Tue, Aug 01, 2017 at 03:11:42PM +0000, Bart Van Assche wrote: > > > On Tue, 2017-08-01 at 18:50 +0800, Ming Lei wrote: > > > > On Tue, Aug 01, 2017 at 06:17:18PM +0800, Ming Lei wrote: > > > > > How can we get the accurate 'number of requests in progress' efficiently? > > > > > > Hello Ming, > > > > > > How about counting the number of bits that have been set in the tag set? > > > I am aware that these bits can be set and/or cleared concurrently with the > > > dispatch code but that count is probably a good starting point. > > > > It has to be atomic_t, which is too too heavy for us, please see the report: > > > > http://marc.info/?t=149868448400003&r=1&w=2 > > > > Both Jens and I want to kill hd_struct.in_flight, but looks still no > > good way. > > Hello Ming, > > Sorry but I disagree that a new atomic variable should be added to keep track > of the number of busy requests. Counting the number of bits that are set in > the tag set should be good enough in this context. That won't work because the tag set is host wide and shared by all LUNs. -- Ming
