Messages in this thread | | | Date | Thu, 14 Oct 2021 16:59:10 +0800 | Subject | Re: [PATCH] mm/vmalloc: fix numa spreading for large hash tables | From | Chen Wandun <> |
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在 2021/10/14 5:46, Shakeel Butt 写道: > On Tue, Sep 28, 2021 at 5:03 AM Chen Wandun <chenwandun@huawei.com> wrote: >> >> Eric Dumazet reported a strange numa spreading info in [1], and found >> commit 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings") introduced >> this issue [2]. >> >> Dig into the difference before and after this patch, page allocation has >> some difference: >> >> before: >> alloc_large_system_hash >> __vmalloc >> __vmalloc_node(..., NUMA_NO_NODE, ...) >> __vmalloc_node_range >> __vmalloc_area_node >> alloc_page /* because NUMA_NO_NODE, so choose alloc_page branch */ >> alloc_pages_current >> alloc_page_interleave /* can be proved by print policy mode */ >> >> after: >> alloc_large_system_hash >> __vmalloc >> __vmalloc_node(..., NUMA_NO_NODE, ...) >> __vmalloc_node_range >> __vmalloc_area_node >> alloc_pages_node /* choose nid by nuam_mem_id() */ >> __alloc_pages_node(nid, ....) >> >> So after commit 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings"), >> it will allocate memory in current node instead of interleaving allocate >> memory. >> >> [1] >> https://lore.kernel.org/linux-mm/CANn89iL6AAyWhfxdHO+jaT075iOa3XcYn9k6JJc7JR2XYn6k_Q@mail.gmail.com/ >> >> [2] >> https://lore.kernel.org/linux-mm/CANn89iLofTR=AK-QOZY87RdUZENCZUT4O6a0hvhu3_EwRMerOg@mail.gmail.com/ >> >> Fixes: 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings") >> Reported-by: Eric Dumazet <edumazet@google.com> >> Signed-off-by: Chen Wandun <chenwandun@huawei.com> >> --- >> mm/vmalloc.c | 33 ++++++++++++++++++++++++++------- >> 1 file changed, 26 insertions(+), 7 deletions(-) >> >> diff --git a/mm/vmalloc.c b/mm/vmalloc.c >> index f884706c5280..48e717626e94 100644 >> --- a/mm/vmalloc.c >> +++ b/mm/vmalloc.c >> @@ -2823,6 +2823,8 @@ vm_area_alloc_pages(gfp_t gfp, int nid, >> unsigned int order, unsigned int nr_pages, struct page **pages) >> { >> unsigned int nr_allocated = 0; >> + struct page *page; >> + int i; >> >> /* >> * For order-0 pages we make use of bulk allocator, if >> @@ -2833,6 +2835,7 @@ vm_area_alloc_pages(gfp_t gfp, int nid, >> if (!order) { > > Can you please replace the above with if (!order && nid != NUMA_NO_NODE)? > >> while (nr_allocated < nr_pages) { >> unsigned int nr, nr_pages_request; >> + page = NULL; >> >> /* >> * A maximum allowed request is hard-coded and is 100 >> @@ -2842,9 +2845,23 @@ vm_area_alloc_pages(gfp_t gfp, int nid, >> */ >> nr_pages_request = min(100U, nr_pages - nr_allocated); >> > > Undo the following change in this if block.
Yes, It seem like more simpler as you suggested, But it still have performance regression, I plan to change the following to consider both mempolcy and alloc_pages_bulk.
Thanks, Wandun
> >> - nr = alloc_pages_bulk_array_node(gfp, nid, >> - nr_pages_request, pages + nr_allocated); >> - >> + if (nid == NUMA_NO_NODE) { >> + for (i = 0; i < nr_pages_request; i++) { >> + page = alloc_page(gfp); >> + if (page) >> + pages[nr_allocated + i] = page; >> + else { >> + nr = i; >> + break; >> + } >> + } >> + if (i >= nr_pages_request) >> + nr = nr_pages_request; >> + } else { >> + nr = alloc_pages_bulk_array_node(gfp, nid, >> + nr_pages_request, >> + pages + nr_allocated); >> + } >> nr_allocated += nr; >> cond_resched(); >> >> @@ -2863,11 +2880,13 @@ vm_area_alloc_pages(gfp_t gfp, int nid, > > Put the following line under "else if (order)" > >> gfp |= __GFP_COMP; >> >> /* High-order pages or fallback path if "bulk" fails. */ >> - while (nr_allocated < nr_pages) { > > Keep the following declarations inside the while loop. > >> - struct page *page; >> - int i; >> >> - page = alloc_pages_node(nid, gfp, order); >> + page = NULL; >> + while (nr_allocated < nr_pages) { >> + if (nid == NUMA_NO_NODE) >> + page = alloc_pages(gfp, order); >> + else >> + page = alloc_pages_node(nid, gfp, order); >> if (unlikely(!page)) >> break; >> >> -- >> 2.25.1 >> > . >
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