On Thu, Jan 20, 2022 at 02:51:40PM +0800, Guangguan Wang wrote: > This implement rq flow control in smc-r link layer. QPs > communicating without rq flow control, in the previous > version, may result in RNR (reveive not ready) error, which > means when sq sends a message to the remote qp, but the > remote qp's rq has no valid rq entities to receive the message. > In RNR condition, the rdma transport layer may retransmit > the messages again and again until the rq has any entities, > which may lower the performance, especially in heavy traffic. > Using credits to do rq flow control can avoid the occurrence > of RNR. > > Test environment: > - CPU Intel Xeon Platinum 8 core, mem 32 GiB, nic Mellanox CX4. > - redis benchmark 6.2.3 and redis server 6.2.3. > - redis server: redis-server --save "" --appendonly no > --protected-mode no --io-threads 7 --io-threads-do-reads yes > - redis client: redis-benchmark -h 192.168.26.36 -q -t set,get > -P 1 --threads 7 -n 2000000 -c 200 -d 10 > > Before: > SET: 205229.23 requests per second, p50=0.799 msec > GET: 212278.16 requests per second, p50=0.751 msec > > After: > SET: 623674.69 requests per second, p50=0.303 msec > GET: 688326.00 requests per second, p50=0.271 msec > > The test of redis-benchmark shows that more than 3X rps > improvement after the implementation of rq flow control. > > Signed-off-by: Guangguan Wang <guangguan.wang@xxxxxxxxxxxxxxxxx> > --- > net/smc/af_smc.c | 12 ++++++ > net/smc/smc_cdc.c | 10 ++++- > net/smc/smc_cdc.h | 3 +- > net/smc/smc_clc.c | 3 ++ > net/smc/smc_clc.h | 3 +- > net/smc/smc_core.h | 17 ++++++++- > net/smc/smc_ib.c | 6 ++- > net/smc/smc_llc.c | 92 +++++++++++++++++++++++++++++++++++++++++++++- > net/smc/smc_llc.h | 5 +++ > net/smc/smc_wr.c | 30 ++++++++++++--- > net/smc/smc_wr.h | 54 ++++++++++++++++++++++++++- > 11 files changed, 222 insertions(+), 13 deletions(-) <...> > + // set peer rq credits watermark, if less than init_credits * 2/3, > + // then credit announcement is needed. <...> > + // set peer rq credits watermark, if less than init_credits * 2/3, > + // then credit announcement is needed. <...> > + // credits have already been announced to peer <...> > + // set local rq credits high watermark to lnk->wr_rx_cnt / 3, > + // if local rq credits more than high watermark, announcement is needed. <...> > +// get one tx credit, and peer rq credits dec <...> > +// put tx credits, when some failures occurred after tx credits got > +// or receive announce credits msgs > +static inline void smc_wr_tx_put_credits(struct smc_link *link, int credits, bool wakeup) <...> > +// to check whether peer rq credits is lower than watermark. > +static inline int smc_wr_tx_credits_need_announce(struct smc_link *link) <...> > +// get local rq credits and set credits to zero. > +// may called when announcing credits > +static inline int smc_wr_rx_get_credits(struct smc_link *link) Please try to use C-style comments. Thanks
