The patch titled
Subject: mm/memory.c: refactor insert_page to prepare for batched-lock insert
has been added to the -mm tree. Its filename is
mm-refactor-insert_page-to-prepare-for-batched-lock-insert.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-refactor-insert_page-to-prepare-for-batched-lock-insert.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-refactor-insert_page-to-prepare-for-batched-lock-insert.patch
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------------------------------------------------------
From: Arjun Roy <arjunroy@xxxxxxxxxx>
Subject: mm/memory.c: refactor insert_page to prepare for batched-lock insert
Add helper methods for vm_insert_page()/insert_page() to prepare for
vm_insert_pages(), which batch-inserts pages to reduce spinlock operations
when inserting multiple consecutive pages into the user page table.
The intention of this patch-set is to reduce atomic ops for tcp zerocopy
receives, which normally hits the same spinlock multiple times
consecutively.
Link: http://lkml.kernel.org/r/20200128025958.43490-1-arjunroy.kdev@xxxxxxxxx
Signed-off-by: Arjun Roy <arjunroy@xxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Soheil Hassas Yeganeh <soheil@xxxxxxxxxx>
Cc: David Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 39 ++++++++++++++++++++++++---------------
1 file changed, 24 insertions(+), 15 deletions(-)
--- a/mm/memory.c~mm-refactor-insert_page-to-prepare-for-batched-lock-insert
+++ a/mm/memory.c
@@ -1430,6 +1430,27 @@ pte_t *__get_locked_pte(struct mm_struct
return pte_alloc_map_lock(mm, pmd, addr, ptl);
}
+static int validate_page_before_insert(struct page *page)
+{
+ if (PageAnon(page) || PageSlab(page) || page_has_type(page))
+ return -EINVAL;
+ flush_dcache_page(page);
+ return 0;
+}
+
+static int insert_page_into_pte_locked(struct mm_struct *mm, pte_t *pte,
+ unsigned long addr, struct page *page, pgprot_t prot)
+{
+ if (!pte_none(*pte))
+ return -EBUSY;
+ /* Ok, finally just insert the thing.. */
+ get_page(page);
+ inc_mm_counter_fast(mm, mm_counter_file(page));
+ page_add_file_rmap(page, false);
+ set_pte_at(mm, addr, pte, mk_pte(page, prot));
+ return 0;
+}
+
/*
* This is the old fallback for page remapping.
*
@@ -1445,26 +1466,14 @@ static int insert_page(struct vm_area_st
pte_t *pte;
spinlock_t *ptl;
- retval = -EINVAL;
- if (PageAnon(page) || PageSlab(page) || page_has_type(page))
+ retval = validate_page_before_insert(page);
+ if (retval)
goto out;
retval = -ENOMEM;
- flush_dcache_page(page);
pte = get_locked_pte(mm, addr, &ptl);
if (!pte)
goto out;
- retval = -EBUSY;
- if (!pte_none(*pte))
- goto out_unlock;
-
- /* Ok, finally just insert the thing.. */
- get_page(page);
- inc_mm_counter_fast(mm, mm_counter_file(page));
- page_add_file_rmap(page, false);
- set_pte_at(mm, addr, pte, mk_pte(page, prot));
-
- retval = 0;
-out_unlock:
+ retval = insert_page_into_pte_locked(mm, pte, addr, page, prot);
pte_unmap_unlock(pte, ptl);
out:
return retval;
_
Patches currently in -mm which might be from arjunroy@xxxxxxxxxx are
mm-refactor-insert_page-to-prepare-for-batched-lock-insert.patch
mm-add-vm_insert_pages.patch
net-zerocopy-use-vm_insert_pages-for-tcp-rcv-zerocopy.patch
