On 3/17/23 12:32, chenjun (AM) wrote: > 在 2023/3/14 22:41, Vlastimil Babka 写道: >>> pc.flags = gfpflags; >>> + >>> + /* >>> + * when (node != NUMA_NO_NODE) && (gfpflags & __GFP_THISNODE) >>> + * 1) try to get a partial slab from target node with __GFP_THISNODE. >>> + * 2) if 1) failed, try to allocate a new slab from target node with >>> + * __GFP_THISNODE. >>> + * 3) if 2) failed, retry 1) and 2) without __GFP_THISNODE constraint. >>> + */ >>> + if (node != NUMA_NO_NODE && !(gfpflags & __GFP_THISNODE) && try_thisnode) >>> + pc.flags |= __GFP_THISNODE; >> >> Hmm I'm thinking we should also perhaps remove direct reclaim possibilities >> from the attempt 2). In your qemu test it should make no difference, as it >> fills everything with kernel memory that is not reclaimable. But in practice >> the target node might be filled with user memory, and I think it's better to >> quickly allocate on a different node than spend time in direct reclaim. So >> the following should work I think? >> >> pc.flags = GFP_NOWAIT | __GFP_NOWARN |__GFP_THISNODE >> > > Hmm, Should it be that: > > pc.flags |= GFP_NOWAIT | __GFP_NOWARN |__GFP_THISNODE No, we need to ignore the other reclaim-related flags that the caller passed, or it wouldn't work as intended. The danger is that we ignore some flag that would be necessary to pass, but I don't think there's any?
