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Message-Id: <20230315051444.3229621-37-willy@infradead.org>
Date: Wed, 15 Mar 2023 05:14:44 +0000
From: "Matthew Wilcox (Oracle)" <willy@...radead.org>
To: linux-arch@...r.kernel.org
Cc: Yin Fengwei <fengwei.yin@...el.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, Matthew Wilcox <willy@...radead.org>
Subject: [PATCH v4 36/36] filemap: Batch PTE mappings
From: Yin Fengwei <fengwei.yin@...el.com>
Call set_pte_range() once per contiguous range of the folio instead
of once per page. This batches the updates to mm counters and the
rmap.
With a will-it-scale.page_fault3 like app (change file write
fault testing to read fault testing. Trying to upstream it to
will-it-scale at [1]) got 15% performance gain on a 48C/96T
Cascade Lake test box with 96 processes running against xfs.
Perf data collected before/after the change:
18.73%--page_add_file_rmap
|
--11.60%--__mod_lruvec_page_state
|
|--7.40%--__mod_memcg_lruvec_state
| |
| --5.58%--cgroup_rstat_updated
|
--2.53%--__mod_lruvec_state
|
--1.48%--__mod_node_page_state
9.93%--page_add_file_rmap_range
|
--2.67%--__mod_lruvec_page_state
|
|--1.95%--__mod_memcg_lruvec_state
| |
| --1.57%--cgroup_rstat_updated
|
--0.61%--__mod_lruvec_state
|
--0.54%--__mod_node_page_state
The running time of __mode_lruvec_page_state() is reduced about 9%.
[1]: https://github.com/antonblanchard/will-it-scale/pull/37
Signed-off-by: Yin Fengwei <fengwei.yin@...el.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
mm/filemap.c | 36 +++++++++++++++++++++++++-----------
1 file changed, 25 insertions(+), 11 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index e2317623dcbf..7a1534460b55 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3483,11 +3483,12 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
struct file *file = vma->vm_file;
struct page *page = folio_page(folio, start);
unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss);
- unsigned int ref_count = 0, count = 0;
+ unsigned int count = 0;
+ pte_t *old_ptep = vmf->pte;
do {
- if (PageHWPoison(page))
- continue;
+ if (PageHWPoison(page + count))
+ goto skip;
if (mmap_miss > 0)
mmap_miss--;
@@ -3497,20 +3498,33 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
* handled in the specific fault path, and it'll prohibit the
* fault-around logic.
*/
- if (!pte_none(*vmf->pte))
- continue;
+ if (!pte_none(vmf->pte[count]))
+ goto skip;
if (vmf->address == addr)
ret = VM_FAULT_NOPAGE;
- ref_count++;
- set_pte_range(vmf, folio, page, 1, addr);
- } while (vmf->pte++, page++, addr += PAGE_SIZE, ++count < nr_pages);
+ count++;
+ continue;
+skip:
+ if (count) {
+ set_pte_range(vmf, folio, page, count, addr);
+ folio_ref_add(folio, count);
+ }
- /* Restore the vmf->pte */
- vmf->pte -= nr_pages;
+ count++;
+ page += count;
+ vmf->pte += count;
+ addr += count * PAGE_SIZE;
+ count = 0;
+ } while (--nr_pages > 0);
+
+ if (count) {
+ set_pte_range(vmf, folio, page, count, addr);
+ folio_ref_add(folio, count);
+ }
- folio_ref_add(folio, ref_count);
+ vmf->pte = old_ptep;
WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss);
return ret;
--
2.39.2
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