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Diffstat (limited to 'Documentation/scheduler/sched-stats.txt')
| -rw-r--r-- | Documentation/scheduler/sched-stats.txt | 154 |
1 files changed, 0 insertions, 154 deletions
diff --git a/Documentation/scheduler/sched-stats.txt b/Documentation/scheduler/sched-stats.txt deleted file mode 100644 index 8259b34a66ae..000000000000 --- a/Documentation/scheduler/sched-stats.txt +++ /dev/null @@ -1,154 +0,0 @@ -Version 15 of schedstats dropped counters for some sched_yield: -yld_exp_empty, yld_act_empty and yld_both_empty. Otherwise, it is -identical to version 14. - -Version 14 of schedstats includes support for sched_domains, which hit the -mainline kernel in 2.6.20 although it is identical to the stats from version -12 which was in the kernel from 2.6.13-2.6.19 (version 13 never saw a kernel -release). Some counters make more sense to be per-runqueue; other to be -per-domain. Note that domains (and their associated information) will only -be pertinent and available on machines utilizing CONFIG_SMP. - -In version 14 of schedstat, there is at least one level of domain -statistics for each cpu listed, and there may well be more than one -domain. Domains have no particular names in this implementation, but -the highest numbered one typically arbitrates balancing across all the -cpus on the machine, while domain0 is the most tightly focused domain, -sometimes balancing only between pairs of cpus. At this time, there -are no architectures which need more than three domain levels. The first -field in the domain stats is a bit map indicating which cpus are affected -by that domain. - -These fields are counters, and only increment. Programs which make use -of these will need to start with a baseline observation and then calculate -the change in the counters at each subsequent observation. A perl script -which does this for many of the fields is available at - - http://eaglet.rain.com/rick/linux/schedstat/ - -Note that any such script will necessarily be version-specific, as the main -reason to change versions is changes in the output format. For those wishing -to write their own scripts, the fields are described here. - -CPU statistics --------------- -cpu<N> 1 2 3 4 5 6 7 8 9 - -First field is a sched_yield() statistic: - 1) # of times sched_yield() was called - -Next three are schedule() statistics: - 2) This field is a legacy array expiration count field used in the O(1) - scheduler. We kept it for ABI compatibility, but it is always set to zero. - 3) # of times schedule() was called - 4) # of times schedule() left the processor idle - -Next two are try_to_wake_up() statistics: - 5) # of times try_to_wake_up() was called - 6) # of times try_to_wake_up() was called to wake up the local cpu - -Next three are statistics describing scheduling latency: - 7) sum of all time spent running by tasks on this processor (in jiffies) - 8) sum of all time spent waiting to run by tasks on this processor (in - jiffies) - 9) # of timeslices run on this cpu - - -Domain statistics ------------------ -One of these is produced per domain for each cpu described. (Note that if -CONFIG_SMP is not defined, *no* domains are utilized and these lines -will not appear in the output.) - -domain<N> <cpumask> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 - -The first field is a bit mask indicating what cpus this domain operates over. - -The next 24 are a variety of load_balance() statistics in grouped into types -of idleness (idle, busy, and newly idle): - - 1) # of times in this domain load_balance() was called when the - cpu was idle - 2) # of times in this domain load_balance() checked but found - the load did not require balancing when the cpu was idle - 3) # of times in this domain load_balance() tried to move one or - more tasks and failed, when the cpu was idle - 4) sum of imbalances discovered (if any) with each call to - load_balance() in this domain when the cpu was idle - 5) # of times in this domain pull_task() was called when the cpu - was idle - 6) # of times in this domain pull_task() was called even though - the target task was cache-hot when idle - 7) # of times in this domain load_balance() was called but did - not find a busier queue while the cpu was idle - 8) # of times in this domain a busier queue was found while the - cpu was idle but no busier group was found - - 9) # of times in this domain load_balance() was called when the - cpu was busy - 10) # of times in this domain load_balance() checked but found the - load did not require balancing when busy - 11) # of times in this domain load_balance() tried to move one or - more tasks and failed, when the cpu was busy - 12) sum of imbalances discovered (if any) with each call to - load_balance() in this domain when the cpu was busy - 13) # of times in this domain pull_task() was called when busy - 14) # of times in this domain pull_task() was called even though the - target task was cache-hot when busy - 15) # of times in this domain load_balance() was called but did not - find a busier queue while the cpu was busy - 16) # of times in this domain a busier queue was found while the cpu - was busy but no busier group was found - - 17) # of times in this domain load_balance() was called when the - cpu was just becoming idle - 18) # of times in this domain load_balance() checked but found the - load did not require balancing when the cpu was just becoming idle - 19) # of times in this domain load_balance() tried to move one or more - tasks and failed, when the cpu was just becoming idle - 20) sum of imbalances discovered (if any) with each call to - load_balance() in this domain when the cpu was just becoming idle - 21) # of times in this domain pull_task() was called when newly idle - 22) # of times in this domain pull_task() was called even though the - target task was cache-hot when just becoming idle - 23) # of times in this domain load_balance() was called but did not - find a busier queue while the cpu was just becoming idle - 24) # of times in this domain a busier queue was found while the cpu - was just becoming idle but no busier group was found - - Next three are active_load_balance() statistics: - 25) # of times active_load_balance() was called - 26) # of times active_load_balance() tried to move a task and failed - 27) # of times active_load_balance() successfully moved a task - - Next three are sched_balance_exec() statistics: - 28) sbe_cnt is not used - 29) sbe_balanced is not used - 30) sbe_pushed is not used - - Next three are sched_balance_fork() statistics: - 31) sbf_cnt is not used - 32) sbf_balanced is not used - 33) sbf_pushed is not used - - Next three are try_to_wake_up() statistics: - 34) # of times in this domain try_to_wake_up() awoke a task that - last ran on a different cpu in this domain - 35) # of times in this domain try_to_wake_up() moved a task to the - waking cpu because it was cache-cold on its own cpu anyway - 36) # of times in this domain try_to_wake_up() started passive balancing - -/proc/<pid>/schedstat ----------------- -schedstats also adds a new /proc/<pid>/schedstat file to include some of -the same information on a per-process level. There are three fields in -this file correlating for that process to: - 1) time spent on the cpu - 2) time spent waiting on a runqueue - 3) # of timeslices run on this cpu - -A program could be easily written to make use of these extra fields to -report on how well a particular process or set of processes is faring -under the scheduler's policies. A simple version of such a program is -available at - http://eaglet.rain.com/rick/linux/schedstat/v12/latency.c |