On Tue, 12 Feb 2019 13:47:24 -0500 Johannes Weiner <han...@cmpxchg.org> wrote:
> On Tue, Feb 12, 2019 at 09:56:45AM -0800, Roman Gushchin wrote: > > The patchset contains few changes to the vmalloc code, which are > > leading to some performance gains and code simplification. > > > > Also, it exports a number of pages, used by vmalloc(), > > in /proc/meminfo. > > > > Patch (1) removes some redundancy on __vunmap(). > > Patch (2) separates memory allocation and data initialization > > in alloc_vmap_area() > > Patch (3) adds vmalloc counter to /proc/meminfo. > > > > v2->v1: > > - rebased on top of current mm tree > > - switch from atomic to percpu vmalloc page counter > > I don't understand what prompted this change to percpu counters. > > All writers already write vmap_area_lock and vmap_area_list, so it's > not really saving much. The for_each_possible_cpu() for /proc/meminfo > on the other hand is troublesome. percpu_counters would fit here. They have probably-unneeded locking but I expect that will be acceptable. And they address the issues with for_each_possible_cpu() avoidance, CPU hotplug and transient negative values.
