Hello,
On Wed, Jun 03, 2015 at 10:29:52PM +0800, Lai Jiangshan wrote:
> tmp_attrs in apply_wqattrs_prepare() is just temporary attrs, we can use
> wq_update_unbound_numa_attrs_buf for it like wq_update_unbound_numa();
>
> The wq_update_unbound_numa_attrs_buf is renamed to wq_calc_node_attrs_buf
> since it is used both for apply_wqattrs_prepare() and
> wq_update_unbound_numa().
>
> The comment for using wq_calc_node_attrs_buf in wq_update_unbound_numa()
> is also moved to the defination of the wq_calc_node_attrs_buf.
>
> This change also avoids frequently alloc/free the tmp_attrs for every
> workqueue when the low level cpumask is being updated.
>
> Signed-off-by: Lai Jiangshan <[email protected]>
> ---
> kernel/workqueue.c | 31 +++++++++++++------------------
> 1 file changed, 13 insertions(+), 18 deletions(-)
>
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 0c2f819..4a40165 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -295,8 +295,13 @@ module_param_named(power_efficient, wq_power_efficient,
> bool, 0444);
>
> static bool wq_numa_enabled; /* unbound NUMA affinity enabled */
>
> -/* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug
> exclusion */
> -static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf;
> +/*
> + * PL: resulted attrs of wq_calc_node_cpumask() for apply_wqattrs_prepare()
> + * and wq_update_unbound_numa().
> + * We don't wanna alloc/free temporary attrs for each call. Let's preallocate
> + * one with the access protection of wq_pool_mutex.
> + */
> +static struct workqueue_attrs *wq_calc_node_attrs_buf;
>
> static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */
> static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
> @@ -3515,7 +3520,7 @@ apply_wqattrs_prepare(struct workqueue_struct *wq,
> const struct workqueue_attrs *attrs)
> {
> struct apply_wqattrs_ctx *ctx;
> - struct workqueue_attrs *new_attrs, *tmp_attrs;
> + struct workqueue_attrs *new_attrs, *tmp_attrs = wq_calc_node_attrs_buf;
Hmm... this actually bothers me a bit. Can we please do something
like the following?
static struct workqueue_attrs *wq_attrs_shared_buf(void)
{
lockdep_assert_held(...);
return __wq_attrs_shared_buf;
}
--
tejun
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