On Fri, 2019-05-31 at 20:03 +0300, Ivan Khoronzhuk wrote: > On Fri, May 31, 2019 at 06:32:41PM +0200, Jesper Dangaard Brouer > wrote: > > On Fri, 31 May 2019 19:25:24 +0300 Ivan Khoronzhuk < > > ivan.khoronzhuk@xxxxxxxxxx> wrote: > > > > > On Fri, May 31, 2019 at 05:46:43PM +0200, Jesper Dangaard Brouer > > > wrote: > > > > From below code snippets, it looks like you only allocated 1 > > > > page_pool > > > > and sharing it with several RX-queues, as I don't have the full > > > > context > > > > and don't know this driver, I might be wrong? > > > > > > > > To be clear, a page_pool object is needed per RX-queue, as it > > > > is > > > > accessing a small RX page cache (which protected by > > > > NAPI/softirq). > > > > > > There is one RX interrupt and one RX NAPI for all rx channels. > > > > So, what are you saying? > > > > You _are_ sharing the page_pool between several RX-channels, but it > > is > > safe because this hardware only have one RX interrupt + NAPI > > instance?? > > I can miss smth but in case of cpsw technically it means: > 1) RX interrupts are disabled while NAPI is scheduled, > not for particular CPU or channel, but at all, for whole cpsw > module. > 2) RX channels are handled one by one by priority. Hi Ivan, I got a silly question.. What is the reason behind having multiple RX rings and one CPU/NAPI handling all of them ? priority ? how do you priorities ? > 3) After all of them handled and no more in budget - interrupts are > enabled. > 4) If page is returned to the pool, and it's within NAPI, no races as > it's > returned protected by softirq. If it's returned not in softirq > it's protected > by producer lock of the ring. > > Probably it's not good example for others how it should be used, not > a big > problem to move it to separate pools.., even don't remember why I > decided to > use shared pool, there was some more reasons... need search in > history. > > > -- > > Best regards, > > Jesper Dangaard Brouer > > MSc.CS, Principal Kernel Engineer at Red Hat > > LinkedIn: http://www.linkedin.com/in/brouer
