Messages in this thread | | | Date | Tue, 3 Sep 2013 18:47:31 -0400 | From | Johannes Weiner <> | Subject | Re: [PATCH RESEND] mm/vmscan : use vmcan_swappiness( ) basing on MEMCG config to elimiate unnecessary runtime cost |
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On Mon, Aug 26, 2013 at 09:36:58PM +0800, larmbr wrote: > Currently, we get the vm_swappiness via vmscan_swappiness(), which > calls global_reclaim() to check if this is a global reclaim. > > Besides, the current implementation of global_reclaim() always returns > true for the !CONFIG_MEGCG case, and judges the other case by checking > whether scan_control->target_mem_cgroup is null or not. > > Thus, we could just use two versions of vmscan_swappiness() based on > MEMCG Kconfig , to eliminate the unnecessary run-time cost for > the !CONFIG_MEMCG at all, and to squash all memcg-related checking > into the CONFIG_MEMCG version.
The compiler can easily detect that global_reclaim() always returns true for !CONFIG_MEMCG during compile time and not even generate a branch for this.
> 2 files changed, 12 insertions(+), 3 deletions(-)
You're adding more code for now gain.
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