From: Li RongQing <lirongq...@baidu.com>
Date: Fri, 27 Jul 2018 16:03:57 +0800
> The size of struct cpumask varies with CONFIG_NR_CPUS, some config
> CONFIG_NR_CPUS is very larger, like 5120, struct cpumask will take
> 640 bytes, if there is thousands of flows, it will take lots of
> memory
>
> cpu_used_mask has two purposes
> 1: Assume first cpu as cpu0 which maybe not true; now use
> cpumask_first(cpu_possible_mask)
> 2: when get/clear statistic, reduce the iteratation; but it
> is not hot path, so use for_each_possible_cpu
>
> Signed-off-by: Zhang Yu <zhangy...@baidu.com>
> Signed-off-by: Li RongQing <lirongq...@baidu.com>
This seems to completely undo the optimization done by:
commit c4b2bf6b4a35348fe6d1eb06928eb68d7b9d99a9
Author: Tonghao Zhang <xiangxia.m....@gmail.com>
Date: Mon Jul 17 23:28:06 2017 -0700
openvswitch: Optimize operations for OvS flow_stats.
And in that commit message it states clearly that flow_free()
performance matters, and that the iteration over cpu_possible_mask in
the for() loop is the problem.
At a minimum, we can't apply this unless you explain why the
above performance issue won't be reintroudced by your change.
Thank you.
