Hi Mike, On 18/1/19 11:29, Mike Snitzer wrote: > On Thu, Jan 18 2018 at 10:09pm -0500, > Joseph Qi <[email protected]> wrote: > >> From: Joseph Qi <[email protected]> >> >> DM device sets QUEUE_FLAG_NONROT after the queue is registered. That is >> to mean, the previous initialization in blk_throtl_register_queue is >> wrong in this case. >> Fix it by checking and then updating the info during root tg >> initialization as we don't have a better choice. >> >> Signed-off-by: Joseph Qi <[email protected]> >> Reviewed-by: Shaohua Li <[email protected]> >> --- >> block/blk-throttle.c | 19 +++++++++++++++++++ >> 1 file changed, 19 insertions(+) >> >> diff --git a/block/blk-throttle.c b/block/blk-throttle.c >> index bf52035..7150f14 100644 >> --- a/block/blk-throttle.c >> +++ b/block/blk-throttle.c >> @@ -541,6 +541,25 @@ static void throtl_pd_init(struct blkg_policy_data *pd) >> if (cgroup_subsys_on_dfl(io_cgrp_subsys) && blkg->parent) >> sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue; >> tg->td = td; >> + >> +#ifdef CONFIG_BLK_DEV_THROTTLING_LOW >> + /* >> + * DM device sets QUEUE_FLAG_NONROT after the queue is registered, >> + * so the previous initialization is wrong in this case. Check and >> + * update it here. >> + */ >> + if (blk_queue_nonrot(blkg->q) && >> + td->filtered_latency != LATENCY_FILTERED_SSD) { >> + int i; >> + >> + td->throtl_slice = DFL_THROTL_SLICE_SSD; >> + td->filtered_latency = LATENCY_FILTERED_SSD; >> + for (i = 0; i < LATENCY_BUCKET_SIZE; i++) { >> + td->avg_buckets[READ][i].latency = 0; >> + td->avg_buckets[WRITE][i].latency = 0; >> + } >> + } >> +#endif >> } >> >> /* >> -- >> 1.9.4 > > This should be fixed for 4.16, please see these block tree commits: > http://git.kernel.dk/cgit/linux-block/commit/?h=for-4.16/block&id=fa70d2e2c4a0a54ced98260c6a176cc94c876d27 > http://git.kernel.dk/cgit/linux-block/commit/?h=for-4.16/block&id=c100ec49fdd2222836ff8a17c7bfcc7611d2ee2b > > The last commit's patch header even references the previous submission > you had for this patch with: > > "These changes also stave off the need to introduce new DM-specific > workarounds in block core, e.g. this proposal: > https://patchwork.kernel.org/patch/10067961/"; > Yes, if we call dm_table_set_restrictions before blk_register_queue now, we can make sure the initialization is correct by checking whether flag QUEUE_FLAG_NONROT is set or not. So my patch is no longer needed. Jens, please ignore this patch, thanks.
Thanks, Joseph
