On Fri, Oct 19, 2018 at 09:38:18AM +0100, Mel Gorman wrote: >On Fri, Oct 19, 2018 at 04:33:03AM +0000, Wei Yang wrote: >> node >> Reply-To: Wei Yang <richard.weiyang@xxxxxxxxx> >> >> Masters, >> >> During the code reading, I pop up this idea. >> >> In case we put some intelegence of NUMA node to pcp->lists[], we may >> get a better performance. >> > >Why? > >> The idea is simple: >> >> Put page on other nodes to the tail of pcp->lists[], because we >> allocate from head and free from tail. >> > >Pages from remote nodes are not placed on local lists. Even in the slab >context, such objects are placed on alien caches which have special >handling. > Hmm... I am not sure get your point correctly. As I mentioned in the reply to Vlastimil, every zone has a per_cpu_pageset for each cpu. For those per_cpu_pageset of one zone, it will only contains pages from this zone. This means, some of per_cpu_pageset will have the pages with the same node id, while others not. I don't get your point for the slab context. They use a different list instead of pcp->lists[]? If you could give me some hint, I may catch up. >> Since my desktop just has one numa node, I couldn't test the effect. > >I suspect it would eventually cause a crash or at least weirdness as the >page zone ids would not match due to different nodes. > If my analysis is correct, there are only two relationship between page node_id of those pages in pcp and the pcp's node_id, either the same or not. Let me have a try with qemu emulated numa system. :-) >> Sorry for sending this without a real justification. Hope this will not >> make you uncomfortable. I would be very glad if you suggest some >> verifications that I could do. >> >> Below is my testing patch, look forward your comments. >> > >I commend you trying to understand how the page allocator works but I >suggest you take a step back, pick a workload that is of interest and >profile it to see where hot spots are that may pinpoint where an >improvement can be made. > >-- >Mel Gorman >SUSE Labs -- Wei Yang Help you, Help me
