lkml.org 
[lkml]   [2015]   [May]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 4/7 V2] workqueue: reuse the current per-node pwq when its attrs unchanged
On Tue, May 12, 2015 at 08:32:32PM +0800, Lai Jiangshan wrote:
> If the cpuamsk is changed, it is possible that only a part of the per-node

cpumask

> pwq is affected. This can happen when the user changes the cpumask of
> a workqueue or the low level cpumask.
>
> So we try to reuse the current per-node pwq when its attrs unchanged.

are unchanged.

> @@ -3592,9 +3593,14 @@ apply_wqattrs_prepare(struct workqueue_struct *wq,
>
> for_each_node(node) {
> if (wq_calc_node_cpumask(new_attrs, node, -1, tmp_attrs->cpumask)) {
> - ctx->pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs);
> - if (!ctx->pwq_tbl[node])
> + pwq = unbound_pwq_by_node(wq, node);
> + if (pwq && wqattrs_equal(tmp_attrs, pwq->pool->attrs))
> + pwq = get_pwq_unlocked(pwq);

Ah, okay, the function gets used here again. BTW, why does this
function return anything? Can this function ever return something
which isn't the pwq it was called with?

> + else
> + pwq = alloc_unbound_pwq(wq, tmp_attrs);
> + if (!pwq)
> goto out_free;

If get_pwq_unlocked() can't fail, why are we testing for NULL pwq
here? This code is kinda misleading.

> + ctx->pwq_tbl[node] = pwq;
> } else {
> ctx->dfl_pwq->refcnt++;
> ctx->pwq_tbl[node] = ctx->dfl_pwq;
> @@ -3739,7 +3745,6 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
> cpumask = target_attrs->cpumask;
>
> copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
> - pwq = unbound_pwq_by_node(wq, node);
>
> /*
> * Let's determine what needs to be done. If the target cpumask is
> @@ -3748,6 +3753,7 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
> * equals the default pwq's, the default pwq should be used.
> */
> if (wq_calc_node_cpumask(wq->dfl_pwq->pool->attrs, node, cpu_off, cpumask)) {
> + pwq = unbound_pwq_by_node(wq, node);

It'd be nice to note this change in the patch description.

Thanks.

--
tejun


\
 
 \ /
  Last update: 2015-05-18 23:21    [W:0.110 / U:1.800 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site