From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754455Ab0DBUyA (ORCPT ); Fri, 2 Apr 2010 16:54:00 -0400 Received: from smtp-out.google.com ([216.239.44.51]:34007 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753824Ab0DBUxx convert rfc822-to-8bit (ORCPT ); Fri, 2 Apr 2010 16:53:53 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:in-reply-to:references:from:date:message-id: subject:to:cc:content-type:content-transfer-encoding:x-system-of-record; b=OODpKZybzHiHAjHLb8DHBeIDtabK5JG7lIVhTIBXHNJm1y6U38GnrF6y+3mCPBRc4 QrfDXKRKy6AAzE9twCh5A== MIME-Version: 1.0 In-Reply-To: <20100402181049.GB3516@redhat.com> References: <20100401215541.2843.79107.stgit@austin.mtv.corp.google.com> <20100401220109.2843.36040.stgit@austin.mtv.corp.google.com> <20100402181049.GB3516@redhat.com> From: Divyesh Shah Date: Fri, 2 Apr 2010 13:53:30 -0700 Message-ID: Subject: Re: [PATCH 2/3] blkio: Add io controller stats like To: Vivek Goyal Cc: jens.axboe@oracle.com, linux-kernel@vger.kernel.org, nauman@google.com, ctalbott@google.com Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 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 >> --- >> >>  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 >