Messages in this thread Patch in this message | | | From | Divyesh Shah <> | Date | Fri, 2 Apr 2010 13:53:30 -0700 | Subject | Re: [PATCH 2/3] blkio: Add io controller stats like |
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Vivek, thanks for the detailed review. Comments inline. I'll send a V2 patchset soon.
On Fri, Apr 2, 2010 at 11:10 AM, Vivek Goyal <vgoyal@redhat.com> wrote: > On Thu, Apr 01, 2010 at 03:01:24PM -0700, Divyesh Shah wrote: >> - io_service_time >> - io_wait_time >> - io_serviced >> - io_service_bytes >> > > Hi Divyesh, > > Some more description what exactly these stats are will be helpful. Please > also update Documentation/cgroup/blkio-controller.txt file appropriately. > Especially, "Details of cgroup files" section.
Done. Will be in V2
> >> These stats are accumulated per operation type helping us to distinguish between >> read and write, and sync and async IO. This patch does not increment any of >> these stats. >> >> Signed-off-by: Divyesh Shah<dpshah@google.com> >> --- >> >> block/blk-cgroup.c | 178 ++++++++++++++++++++++++++++++++++++++++++++++----- >> block/blk-cgroup.h | 39 +++++++++-- >> block/cfq-iosched.c | 2 - >> 3 files changed, 194 insertions(+), 25 deletions(-) >> >> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c >> index 5be3981..ad6843f 100644 >> --- a/block/blk-cgroup.c >> +++ b/block/blk-cgroup.c >> @@ -55,12 +55,15 @@ struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup) >> } >> EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup); >> >> -void blkiocg_update_blkio_group_stats(struct blkio_group *blkg, >> - unsigned long time) >> +void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time) >> { >> - blkg->time += time; >> + unsigned long flags; >> + >> + spin_lock_irqsave(&blkg->stats_lock, flags); >> + blkg->stats.time += time; >> + spin_unlock_irqrestore(&blkg->stats_lock, flags); >> } >> -EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_stats); >> +EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used); >> >> void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg, >> struct blkio_group *blkg, void *key, dev_t dev) >> @@ -170,13 +173,121 @@ blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val) >> return 0; >> } >> >> -#define SHOW_FUNCTION_PER_GROUP(__VAR) \ >> +static int >> +blkiocg_reset_write(struct cgroup *cgroup, struct cftype *cftype, u64 val) >> +{ >> + struct blkio_cgroup *blkcg; >> + struct blkio_group *blkg; >> + struct hlist_node *n; >> + struct blkio_group_stats *stats; >> + >> + blkcg = cgroup_to_blkio_cgroup(cgroup); >> + spin_lock_irq(&blkcg->lock); >> + hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { >> + spin_lock(&blkg->stats_lock); >> + stats = &blkg->stats; >> + memset(stats, 0, sizeof(struct blkio_group_stats)); >> + spin_unlock(&blkg->stats_lock); >> + } >> + spin_unlock_irq(&blkcg->lock); >> + return 0; >> +} >> + >> +void get_key_name(int type, char *disk_id, char *str, int chars_left) >> +{ > > get_key_name() should be static? Can we prefix all these internal function > names with blkio? Done. Will be in V2.
> > Do we have to introduce this separate notion of char *disk_id. Can we > simply stick to dev_t and do the sprintf like functions to convert that > into key. For me personally it is just less confusion while reading code. > >> + strlcpy(str, disk_id, chars_left); >> + chars_left -= strlen(str); >> + if (chars_left <= 0) { >> + printk(KERN_WARNING >> + "Possibly incorrect cgroup stat display format"); >> + return; >> + } >> + switch (type) { >> + case IO_READ: >> + strlcat(str, " Read", chars_left); >> + break; >> + case IO_WRITE: >> + strlcat(str, " Write", chars_left); >> + break; >> + case IO_SYNC: >> + strlcat(str, " Sync", chars_left); >> + break; >> + case IO_ASYNC: >> + strlcat(str, " Async", chars_left); >> + break; >> + case IO_TYPE_MAX: >> + strlcat(str, " Total", chars_left); >> + break; > > Should we use IO_TYPE_TOTAL for "Total" stats.
Can certainly replace MAX with TOTAL.
> >> + default: >> + strlcat(str, " Invalid", chars_left); >> + } >> +} >> + >> +typedef uint64_t (get_var) (struct blkio_group *, int); >> + >> +#define MAX_KEY_LEN 100 > > Can we move above define to the beginning of the file. So that it is > easily visible. Done > >> +uint64_t get_typed_stat(struct blkio_group *blkg, struct cgroup_map_cb *cb, >> + get_var *getvar, char *disk_id) >> +{ > > static function? blkio_get_typed_stat()? Done > > Again, can we use dev_t instead of char *disk_id. Good point. Done > >> + uint64_t disk_total; >> + char key_str[MAX_KEY_LEN]; >> + int type; >> + >> + for (type = 0; type < IO_TYPE_MAX; type++) { >> + get_key_name(type, disk_id, key_str, MAX_KEY_LEN); >> + cb->fill(cb, key_str, getvar(blkg, type)); >> + } >> + disk_total = getvar(blkg, IO_READ) + getvar(blkg, IO_WRITE); >> + get_key_name(IO_TYPE_MAX, disk_id, key_str, MAX_KEY_LEN); >> + cb->fill(cb, key_str, disk_total); >> + return disk_total; >> +} >> + >> +uint64_t get_stat(struct blkio_group *blkg, struct cgroup_map_cb *cb, >> + get_var *getvar, char *disk_id) >> +{ >> + uint64_t var = getvar(blkg, 0); >> + cb->fill(cb, disk_id, var); >> + return var; >> +} >> + >> +#define GET_STAT_INDEXED(__VAR) \ >> +uint64_t get_##__VAR##_stat(struct blkio_group *blkg, int type) \ >> +{ \ >> + return blkg->stats.__VAR[type]; \ >> +} \ >> + >> +GET_STAT_INDEXED(io_service_bytes); >> +GET_STAT_INDEXED(io_serviced); >> +GET_STAT_INDEXED(io_service_time); >> +GET_STAT_INDEXED(io_wait_time); >> +#undef GET_STAT_INDEXED >> + >> +#define GET_STAT(__VAR, __CONV) \ >> +uint64_t get_##__VAR##_stat(struct blkio_group *blkg, int dummy) \ >> +{ \ >> + uint64_t data = blkg->stats.__VAR; \ >> + if (__CONV) \ >> + data = (uint64_t)jiffies_to_msecs(data) * NSEC_PER_MSEC;\ >> + return data; \ >> +} >> + >> +GET_STAT(time, 1); >> +GET_STAT(sectors, 0); >> +#ifdef CONFIG_DEBUG_BLK_CGROUP >> +GET_STAT(dequeue, 0); >> +#endif >> +#undef GET_STAT >> + > > I think now so many macros to define different kind of functions is > becoming really confusing. How about creating a two dimensional stat > array which is indexed by type of io stat like "io_service_time" and > then indexed by sub io type that is "READ, WRITE, SYNC" etc. And we > can define a single function to read all kind of stats. > > That way we will not have to define one GET_STAT_INDEXED() and GET_STAT() > for each unindexed variable. If there are not multiple functions then, > then everywhere we don't have to pass around a function pointer to read > the variable stat and code should become much simpler. Example, code > follows. > > > enum stat_type { > BLKIO_STAT_TIME > BLKIO_STAT_SECTORS > BLKIO_STAT_WAIT_TIME > BLKIO_STAT_SERVICE_TIME > } > > enum stat_sub_type { > BLKIO_STAT_READ > BLKIO_STAT_WRITE > BLKIO_STAT_SYNC > } > > blkio_get_stat_var(enum stat_type var, enum stat_sub_type var_type) { > > if (var == BLKIO_STAT_TIME) > reutrn blkg->stat.time > > /* Same as above for sectors */ > > return blkg->stat[var][var_type]; > }
I'm not sure adding this level of complexity (2nd dimension for stats) and the numerous if (..) statements (or switch) is warranted when they only apply for the get_stat() and get_typed_stat() functions. This seems like a more complicated simplification :).
> > Also all these get_* function needs to be static. Done > >> +#define SHOW_FUNCTION_PER_GROUP(__VAR, get_stats, getvar, show_total) \ >> static int blkiocg_##__VAR##_read(struct cgroup *cgroup, \ >> - struct cftype *cftype, struct seq_file *m) \ >> + struct cftype *cftype, struct cgroup_map_cb *cb) \ >> { \ >> struct blkio_cgroup *blkcg; \ >> struct blkio_group *blkg; \ >> struct hlist_node *n; \ >> + uint64_t cgroup_total = 0; \ >> + char disk_id[10]; \ >> \ >> if (!cgroup_lock_live_group(cgroup)) \ >> return -ENODEV; \ >> @@ -184,19 +295,32 @@ static int blkiocg_##__VAR##_read(struct cgroup *cgroup, \ >> blkcg = cgroup_to_blkio_cgroup(cgroup); \ >> rcu_read_lock(); \ >> hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {\ >> - if (blkg->dev) \ >> - seq_printf(m, "%u:%u %lu\n", MAJOR(blkg->dev), \ >> - MINOR(blkg->dev), blkg->__VAR); \ >> + if (blkg->dev) { \ >> + spin_lock_irq(&blkg->stats_lock); \ >> + snprintf(disk_id, 10, "%u:%u", MAJOR(blkg->dev),\ >> + MINOR(blkg->dev)); \ >> + cgroup_total += get_stats(blkg, cb, getvar, \ >> + disk_id); \ >> + spin_unlock_irq(&blkg->stats_lock); \ >> + } \ >> } \ >> + if (show_total) \ >> + cb->fill(cb, "Total", cgroup_total); \ >> rcu_read_unlock(); \ >> cgroup_unlock(); \ >> return 0; \ >> } >> >> -SHOW_FUNCTION_PER_GROUP(time); >> -SHOW_FUNCTION_PER_GROUP(sectors); >> +SHOW_FUNCTION_PER_GROUP(time, get_stat, get_time_stat, 0); >> +SHOW_FUNCTION_PER_GROUP(sectors, get_stat, get_sectors_stat, 0); >> +SHOW_FUNCTION_PER_GROUP(io_service_bytes, get_typed_stat, >> + get_io_service_bytes_stat, 1); >> +SHOW_FUNCTION_PER_GROUP(io_serviced, get_typed_stat, get_io_serviced_stat, 1); >> +SHOW_FUNCTION_PER_GROUP(io_service_time, get_typed_stat, >> + get_io_service_time_stat, 1); >> +SHOW_FUNCTION_PER_GROUP(io_wait_time, get_typed_stat, get_io_wait_time_stat, 1); >> #ifdef CONFIG_DEBUG_BLK_CGROUP >> -SHOW_FUNCTION_PER_GROUP(dequeue); >> +SHOW_FUNCTION_PER_GROUP(dequeue, get_stat, get_dequeue_stat, 0); >> #endif >> #undef SHOW_FUNCTION_PER_GROUP >> >> @@ -204,7 +328,7 @@ SHOW_FUNCTION_PER_GROUP(dequeue); >> void blkiocg_update_blkio_group_dequeue_stats(struct blkio_group *blkg, >> unsigned long dequeue) >> { >> - blkg->dequeue += dequeue; >> + blkg->stats.dequeue += dequeue; >> } >> EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_dequeue_stats); >> #endif >> @@ -217,16 +341,38 @@ struct cftype blkio_files[] = { >> }, >> { >> .name = "time", >> - .read_seq_string = blkiocg_time_read, >> + .read_map = blkiocg_time_read, >> + .write_u64 = blkiocg_reset_write, >> }, >> { >> .name = "sectors", >> - .read_seq_string = blkiocg_sectors_read, >> + .read_map = blkiocg_sectors_read, >> + .write_u64 = blkiocg_reset_write, >> + }, >> + { >> + .name = "io_service_bytes", >> + .read_map = blkiocg_io_service_bytes_read, >> + .write_u64 = blkiocg_reset_write, >> + }, >> + { >> + .name = "io_serviced", >> + .read_map = blkiocg_io_serviced_read, >> + .write_u64 = blkiocg_reset_write, >> + }, >> + { >> + .name = "io_service_time", >> + .read_map = blkiocg_io_service_time_read, >> + .write_u64 = blkiocg_reset_write, >> + }, >> + { >> + .name = "io_wait_time", >> + .read_map = blkiocg_io_wait_time_read, >> + .write_u64 = blkiocg_reset_write, >> }, > > blkiocg_reset_write() is invoked if a user does some write on any of the > above files. This will reset all the stats. So if I do echo x > > blkio.time, I will see all other files being reset? I think this is > little counter intutive. > > Either we need to reset only those specific stats (the file being written > to) or may be we can provide a separate file "blkio.reset_stats" to reset > all the stats?
I added a note in the Documentation file that writing an int to any of the stats should reset all. I don't get the point of introducing another file for this and would want stats to be cleared all together in order to have say io_service_time and io_serviced in sync, i.e., the io_service_time should always be the total service time for the IOs accounted for in io_serviced.
> Secondly, instead of providing separate files for all the stats > "io_service_bytes, io_serviced...." do you think it makes sense to put > these in a single file "blkio.stat". Something like what memory controller > does for providing stats in a single file. I think number of files per > cgroup will be little less overwhelming that way. > > Thinking loud, Hm.., but these stats are per device (unlink memory cgroup) > that too each stat has been broken down by type (READ, WRITE, SYNC..etc), so it > might be too much of info in a single file. That way, keeping these in > separate files makese sense. I guess, per stat file is ok, given the > fact that stats are per device.
Yeah we'd rather keep them separate. > > Thanks > Vivek > >> #ifdef CONFIG_DEBUG_BLK_CGROUP >> { >> .name = "dequeue", >> - .read_seq_string = blkiocg_dequeue_read, >> + .read_map = blkiocg_dequeue_read, >> }, >> #endif >> }; >> diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h >> index fe44517..5c5e529 100644 >> --- a/block/blk-cgroup.h >> +++ b/block/blk-cgroup.h >> @@ -23,6 +23,14 @@ extern struct cgroup_subsys blkio_subsys; >> #define blkio_subsys_id blkio_subsys.subsys_id >> #endif >> >> +enum io_type { >> + IO_READ = 0, >> + IO_WRITE, >> + IO_SYNC, >> + IO_ASYNC, >> + IO_TYPE_MAX >> +}; >> + >> struct blkio_cgroup { >> struct cgroup_subsys_state css; >> unsigned int weight; >> @@ -30,6 +38,23 @@ struct blkio_cgroup { >> struct hlist_head blkg_list; >> }; >> >> +struct blkio_group_stats { >> + /* total disk time and nr sectors dispatched by this group */ >> + uint64_t time; >> + uint64_t sectors; >> + /* Total disk time used by IOs in ns */ >> + uint64_t io_service_time[IO_TYPE_MAX]; >> + uint64_t io_service_bytes[IO_TYPE_MAX]; /* Total bytes transferred */ >> + /* Total IOs serviced, post merge */ >> + uint64_t io_serviced[IO_TYPE_MAX]; >> + /* Total time spent waiting in scheduler queue in ns */ >> + uint64_t io_wait_time[IO_TYPE_MAX]; >> +#ifdef CONFIG_DEBUG_BLK_CGROUP >> + /* How many times this group has been removed from service tree */ >> + unsigned long dequeue; >> +#endif >> +}; >> + >> struct blkio_group { >> /* An rcu protected unique identifier for the group */ >> void *key; >> @@ -38,15 +63,13 @@ struct blkio_group { >> #ifdef CONFIG_DEBUG_BLK_CGROUP >> /* Store cgroup path */ >> char path[128]; >> - /* How many times this group has been removed from service tree */ >> - unsigned long dequeue; >> #endif >> /* The device MKDEV(major, minor), this group has been created for */ >> dev_t dev; >> >> - /* total disk time and nr sectors dispatched by this group */ >> - unsigned long time; >> - unsigned long sectors; >> + /* Need to serialize the stats in the case of reset/update */ >> + spinlock_t stats_lock; >> + struct blkio_group_stats stats; >> }; >> >> typedef void (blkio_unlink_group_fn) (void *key, struct blkio_group *blkg); >> @@ -105,8 +128,8 @@ extern void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg, >> extern int blkiocg_del_blkio_group(struct blkio_group *blkg); >> extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, >> void *key); >> -void blkiocg_update_blkio_group_stats(struct blkio_group *blkg, >> - unsigned long time); >> +void blkiocg_update_timeslice_used(struct blkio_group *blkg, >> + unsigned long time); >> #else >> struct cgroup; >> static inline struct blkio_cgroup * >> @@ -122,7 +145,7 @@ blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; } >> >> static inline struct blkio_group * >> blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; } >> -static inline void blkiocg_update_blkio_group_stats(struct blkio_group *blkg, >> +static inline void blkiocg_update_timeslice_used(struct blkio_group *blkg, >> unsigned long time) {} >> #endif >> #endif /* _BLK_CGROUP_H */ >> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c >> index c18e348..d91df9f 100644 >> --- a/block/cfq-iosched.c >> +++ b/block/cfq-iosched.c >> @@ -914,7 +914,7 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, >> >> cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, >> st->min_vdisktime); >> - blkiocg_update_blkio_group_stats(&cfqg->blkg, used_sl); >> + blkiocg_update_timeslice_used(&cfqg->blkg, used_sl); >> } >> >> #ifdef CONFIG_CFQ_GROUP_IOSCHED > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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