The patch titled
Subject: mm: move more expensive part of XA setup out of mapping check
has been added to the -mm tree. Its filename is
mm-move-more-expensive-part-of-xa-setup-out-of-mapping-check.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-move-more-expensive-part-of-xa-setup-out-of-mapping-check.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-move-more-expensive-part-of-xa-setup-out-of-mapping-check.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Jens Axboe <axboe@xxxxxxxxx>
Subject: mm: move more expensive part of XA setup out of mapping check
The fast path here is not needing any writeback, yet we spend time setting
up the xarray lookup data upfront. Move the part that actually needs to
iterate the address space mapping into a separate helper, saving ~30% of
the time here.
Link: https://lkml.kernel.org/r/49f67983-b802-8929-edab-d807f745c9ca@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 43 +++++++++++++++++++++++++------------------
1 file changed, 25 insertions(+), 18 deletions(-)
--- a/mm/filemap.c~mm-move-more-expensive-part-of-xa-setup-out-of-mapping-check
+++ a/mm/filemap.c
@@ -639,6 +639,30 @@ static bool mapping_needs_writeback(stru
return mapping->nrpages;
}
+static bool filemap_range_has_writeback(struct address_space *mapping,
+ loff_t start_byte, loff_t end_byte)
+{
+ XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);
+ pgoff_t max = end_byte >> PAGE_SHIFT;
+ struct page *page;
+
+ if (end_byte < start_byte)
+ return false;
+
+ rcu_read_lock();
+ xas_for_each(&xas, page, max) {
+ if (xas_retry(&xas, page))
+ continue;
+ if (xa_is_value(page))
+ continue;
+ if (PageDirty(page) || PageLocked(page) || PageWriteback(page))
+ break;
+ }
+ rcu_read_unlock();
+ return page != NULL;
+
+}
+
/**
* filemap_range_needs_writeback - check if range potentially needs writeback
* @mapping: address space within which to check
@@ -656,29 +680,12 @@ static bool mapping_needs_writeback(stru
bool filemap_range_needs_writeback(struct address_space *mapping,
loff_t start_byte, loff_t end_byte)
{
- XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);
- pgoff_t max = end_byte >> PAGE_SHIFT;
- struct page *page;
-
if (!mapping_needs_writeback(mapping))
return false;
if (!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK))
return false;
- if (end_byte < start_byte)
- return false;
-
- rcu_read_lock();
- xas_for_each(&xas, page, max) {
- if (xas_retry(&xas, page))
- continue;
- if (xa_is_value(page))
- continue;
- if (PageDirty(page) || PageLocked(page) || PageWriteback(page))
- break;
- }
- rcu_read_unlock();
- return page != NULL;
+ return filemap_range_has_writeback(mapping, start_byte, end_byte);
}
EXPORT_SYMBOL_GPL(filemap_range_needs_writeback);
_
Patches currently in -mm which might be from axboe@xxxxxxxxx are
mm-move-more-expensive-part-of-xa-setup-out-of-mapping-check.patch
