On 05/22/18 16:48, Jianchao Wang wrote: > Currently, kyber is very unfriendly with merging. kyber depends > on ctx rq_list to do merging, however, most of time, it will not > leave any requests in ctx rq_list. This is because even if tokens > of one domain is used up, kyber will try to dispatch requests > from other domain and flush the rq_list there. > > To improve this, we setup kyber_ctx_queue (kcq) which is similar > with ctx, but it has rq_lists for different domain and build same > mapping between kcq and khd as the ctx & hctx. Then we could merge, > insert and dispatch for different domains separately. If one domain > token is used up, the requests could be left in the rq_list of > that domain and maybe merged with following io. > > Following is my test result on machine with 8 cores and NVMe card > INTEL SSDPEKKR128G7 > > fio size=256m ioengine=libaio iodepth=64 direct=1 numjobs=8 > seq/random > +------+---------------------------------------------------------------+ > |patch?| bw(MB/s) | iops | slat(usec) | clat(usec) | merge | > +----------------------------------------------------------------------+ > | w/o | 606/612 | 151k/153k | 6.89/7.03 | 3349.21/3305.40 | 0/0 | > +----------------------------------------------------------------------+ > | w/ | 1083/616 | 277k/154k | 4.93/6.95 | 1830.62/3279.95 | 223k/3k | > +----------------------------------------------------------------------+ > When set numjobs to 16, the bw and iops could reach 1662MB/s and 425k > on my platform. > > Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx> <snip> This looks great but prevents kyber from being built as module, which is AFAIK supposed to work (and works now): .. CC [M] block/kyber-iosched.o Building modules, stage 2. MODPOST 313 modules ERROR: "bio_attempt_back_merge" [block/kyber-iosched.ko] undefined! ERROR: "bio_attempt_front_merge" [block/kyber-iosched.ko] undefined! ERROR: "bio_attempt_discard_merge" [block/kyber-iosched.ko] undefined! ERROR: "blk_try_merge" [block/kyber-iosched.ko] undefined! ERROR: "blk_rq_merge_ok" [block/kyber-iosched.ko] undefined! .. It does build fine when compiled in, obviously. :) cheers, Holger
