On Monday, October 10/05/15, 2015 at 07:09:27 -0700, Ananyev, Konstantin wrote: > Hi Rahul,
[...] > > > > This additional check seems redundant for single segment > > > > packets since rte_pktmbuf_free_seg also performs rte_mbuf_sanity_check. > > > > > > > > Several PMDs already prefer to use rte_pktmbuf_free_seg directly over > > > > rte_pktmbuf_free as it is faster. > > > > > > Other PMDs use rte_pktmbuf_free_seg() as each TD has an associated > > > with it segment. So as HW is done with the TD, SW frees associated > > > segment. > > > In your case I don't see any point in re-implementing rte_pktmbuf_free() > > > manually, > > > and I don't think it would be any faster. > > > > > > Konstantin > > > > As I mentioned below, I am clearly seeing a difference of 1 Mpps. And 1 > > Mpps is not a small difference IMHO. > > Agree with you here - it is a significant difference. > > > > > When running l3fwd with 8 queues, I also collected a perf report. > > When using rte_pktmbuf_free, I see that it eats up around 6% cpu as > > below in perf top report:- > > -------------------- > > 32.00% l3fwd [.] cxgbe_poll > > 22.25% l3fwd [.] t4_eth_xmit > > 20.30% l3fwd [.] main_loop > > 6.77% l3fwd [.] rte_pktmbuf_free > > 4.86% l3fwd [.] refill_fl_usembufs > > 2.00% l3fwd [.] write_sgl > > ..... > > -------------------- > > > > While, when using rte_pktmbuf_free_seg directly, I don't see above > > problem. perf top report now comes as:- > > ------------------- > > 33.36% l3fwd [.] cxgbe_poll > > 32.69% l3fwd [.] t4_eth_xmit > > 19.05% l3fwd [.] main_loop > > 5.21% l3fwd [.] refill_fl_usembufs > > 2.40% l3fwd [.] write_sgl > > .... > > ------------------- > > I don't think these 6% disappeared anywhere. > As I can see, now t4_eth_xmit() increased by roughly same amount > (you still have same job to do). Right. > To me it looks like in that case compiler didn't really inline > rte_pktmbuf_free(). > Wonder can you add 'always_inline' attribute to the rte_pktmbuf_free(), > and see would it make any difference? > > Konstantin I will try out above and update further. Thanks, Rahul.
