On Sun, Oct 20, 2019 at 10:44:10PM +0000, Christopher Lameter wrote: > On Thu, 17 Oct 2019, Roman Gushchin wrote: > > > But if some counters are in bytes (and the next commit in the series > > will convert slab counters to bytes), it's not gonna work: > > value in bytes can easily exceed s8 without exceeding the threshold > > converted to bytes. So to avoid overfilling per-cpu caches and breaking > > vmstats correctness, let's use s32 instead. > > This quardruples the cache footprint of the counters and likely has some > influence on performance. But otherwise slab allocation counters will be flushed too often, which will be likely noticeable. I can do custom s32 buffers only for these counters, but to me it seems like an unnecessary complication, unless we'll find a clear regression. Sp far I haven't noticed any regression on the set of workloads where I did test the patchset, but if you know any benchmark or realistic test which can affected by this check, I'll be happy to try. Also, less-than-word-sized operations can be slower on some platforms.
