Hi On Thu, Jun 27, 2013 at 9:59 AM, Tejun Heo <tj@xxxxxxxxxx> wrote: > (cc'ing Jens) > > Hello, > > This one probably needs -stable cc'd. Jens, do you wanna take this? > If not, I'll be happy to take it through cgroup tree. Personally I think it should not go to -stable. The stats was changed in 3.5 kernel and nobody complained about it, so I guess nobody (except us) cares about the file format. > On Thu, Jun 27, 2013 at 09:37:26AM -0700, Anatol Pomozov wrote: >> Before 3.5 CFQ cgroups stats was lazy initialized - the stat object was created >> only if the device had any I/O in that cgroup. >> >> Around 3.5 time CFQ stat structure became part of device structure. And >> zero stat is created when device is initialized. Initialization can happen >> e.g. when we configure it via 'weight_device' file. It calls >> cfqg_set_weight_device() and it creates cfq_group structure. >> >> But even if device is initialized the stats is still zero. >> If we configure all devices in all in all cgroups it generates a lot of >> useless stat info that takes more resources to process and store. Imagine >> servers with handreds cgroups and handreds iSCSI block devices. >> >> Do not print stats for inactive devices - it restores functionality >> that was before 3.5 >> >> Signed-off-by: Anatol Pomozov <anatol.pomozov@xxxxxxxxx> > > Acked-by: Tejun Heo <tj@xxxxxxxxxx> > >> --- >> block/blk-cgroup.c | 13 +++++++++---- >> 1 file changed, 9 insertions(+), 4 deletions(-) >> >> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c >> index e8918ff..4e07e73 100644 >> --- a/block/blk-cgroup.c >> +++ b/block/blk-cgroup.c >> @@ -560,6 +560,7 @@ EXPORT_SYMBOL_GPL(__blkg_prfill_u64); >> * @rwstat: rwstat to print >> * >> * Print @rwstat to @sf for the device assocaited with @pd. >> + * Devices with zero activity will not be printed. >> */ >> u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, >> const struct blkg_rwstat *rwstat) >> @@ -571,19 +572,23 @@ u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, >> [BLKG_RWSTAT_ASYNC] = "Async", >> }; >> const char *dname = blkg_dev_name(pd->blkg); >> - u64 v; >> + u64 total; >> int i; >> >> if (!dname) >> return 0; >> >> + total = rwstat->cnt[BLKG_RWSTAT_READ] + rwstat->cnt[BLKG_RWSTAT_WRITE]; >> + /* skip devices with no activity */ >> + if (!total) >> + return 0; >> + >> for (i = 0; i < BLKG_RWSTAT_NR; i++) >> seq_printf(sf, "%s %s %llu\n", dname, rwstr[i], >> (unsigned long long)rwstat->cnt[i]); >> >> - v = rwstat->cnt[BLKG_RWSTAT_READ] + rwstat->cnt[BLKG_RWSTAT_WRITE]; >> - seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v); >> - return v; >> + seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)total); >> + return total; >> } >> EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat); >> >> -- >> 1.8.3 >> > > -- > tejun -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
