Re: [patch 1/2] sched: move periodic share updates to entity_tick()
From: Paul Turner
Date: Mon Jan 10 2011 - 18:50:00 EST
Back from the Holidays and catching up on email -- Peter, looks like
this fix still needs merging?
On Thu, Dec 16, 2010 at 6:26 AM, Mike Galbraith <efault@xxxxxx> wrote:
> On Thu, 2010-12-16 at 12:03 +0100, Peter Zijlstra wrote:
>> I made that:
>
> Box is ill, I'll test these as soon as it's all better.
>
>> ---
>> Subject: sched: Move periodic share updates to entity_tick()
>> From: Paul Turner <pjt@xxxxxxxxxx>
>> Date: Wed, 15 Dec 2010 19:10:17 -0800
>>
>> Long running entities that do not block (dequeue) require periodic updates to
>> maintain accurate share values. (Note: group entities with several threads are
>> quite likely to be non-blocking in many circumstances).
>>
>> By virtue of being long-running however, we will see entity ticks (otherwise
>> the required update occurs in dequeue/put and we are done). Thus we can move
>> the detection (and associated work) for these updates into the periodic path.
>>
>> This restores the 'atomicity' of update_curr() with respect to accounting.
>>
>> Signed-off-by: Paul Turner <pjt@xxxxxxxxxx>
>> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
>> LKML-Reference: <20101216031038.067028969@xxxxxxxxxx>
>> ---
>> kernel/sched_fair.c | 21 +++++++++++++++++----
>> 1 file changed, 17 insertions(+), 4 deletions(-)
>>
>> Index: linux-2.6/kernel/sched_fair.c
>> ===================================================================
>> --- linux-2.6.orig/kernel/sched_fair.c
>> +++ linux-2.6/kernel/sched_fair.c
>> @@ -564,10 +564,6 @@ __update_curr(struct cfs_rq *cfs_rq, str
>>
>> #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
>> cfs_rq->load_unacc_exec_time += delta_exec;
>> - if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
>> - update_cfs_load(cfs_rq, 0);
>> - update_cfs_shares(cfs_rq, 0);
>> - }
>> #endif
>> }
>>
>> @@ -809,6 +805,14 @@ static void update_cfs_shares(struct cfs
>>
>> reweight_entity(cfs_rq_of(se), se, shares);
>> }
>> +
>> +static void update_entity_shares_tick(struct cfs_rq *cfs_rq)
>> +{
>> + if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
>> + update_cfs_load(cfs_rq, 0);
>> + update_cfs_shares(cfs_rq, 0);
>> + }
>> +}
>> #else /* CONFIG_FAIR_GROUP_SCHED */
>> static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
>> {
>> @@ -817,6 +821,10 @@ static void update_cfs_load(struct cfs_r
>> static inline void update_cfs_shares(struct cfs_rq *cfs_rq, long weight_delta)
>> {
>> }
>> +
>> +static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
>> +{
>> +}
>> #endif /* CONFIG_FAIR_GROUP_SCHED */
>>
>> static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
>> @@ -1133,6 +1141,11 @@ entity_tick(struct cfs_rq *cfs_rq, struc
>> */
>> update_curr(cfs_rq);
>>
>> + /*
>> + * Update share accounting for long-running entities.
>> + */
>> + update_entity_shares_tick(cfs_rq);
>> +
>> #ifdef CONFIG_SCHED_HRTICK
>> /*
>> * queued ticks are scheduled to match the slice, so don't bother
>>
>
>
>
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