Sudeep Holla <sudeep.holla@xxxxxxx> writes: > On Wed, Sep 20, 2023 at 02:18:48PM +0800, Huang Ying wrote: >> Per-CPU data cache size is useful information. For example, it can be >> used to determine per-CPU cache size. So, in this patch, the data >> cache size for each CPU is calculated via data_cache_size / >> shared_cpu_weight. >> >> A brute-force algorithm to iterate all online CPUs is used to avoid >> to allocate an extra cpumask, especially in offline callback. >> > > You have not mentioned who will use this information ? Looking at the > change, it is not exposed to the user-space. Also I see this is actually > part of the series [1]. Is this info used in any of those patches ? Can you > point me to the same ? Yes. It is used by [PATCH 03/10] of the series. If the per-CPU data cache size is large enough, we will cache more pages in the per-CPU pageset to reduce the zone lock contention. > Not all architecture use cacheinfo yet. How will the mm changes affect those > platforms ? If cacheinfo isn't available, we will fallback to the original behavior. That is, we will drain per-CPU pageset more often (that is, cache less to improve cache-hot pages sharing between CPUs). > -- > Regards, > Sudeep > > [1] https://lore.kernel.org/all/20230920061856.257597-1-ying.huang@xxxxxxxxx/ -- Best Regards, Huang, Ying
