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radix-tree: delete radix_tree_range_tag_if_tagged()

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This is an exceptionally complicated function with just one caller
(tag_pages_for_writeback).  We devote a large portion of the runtime of
the test suite to testing this one function which has one caller.  By
introducing the new function radix_tree_iter_tag_set(), we can eliminate
all of the complexity while keeping the performance.  The caller can now
use a fairly standard radix_tree_for_each() loop, and it doesn't need to
worry about tricksy things like 'start' wrapping.

The test suite continues to spend a large amount of time investigating
this function, but now it's testing the underlying primitives such as
radix_tree_iter_resume() and the radix_tree_for_each_tagged() iterator
which are also used by other parts of the kernel.

Link: http://lkml.kernel.org/r/1480369871-5271-57-git-send-email-mawilcox@linuxonhyperv.com
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox
2016-12-14 15:08:55 -08:00
committed by Linus Torvalds
parent 478922e2b0
commit 268f42de71
9 changed files with 124 additions and 162 deletions
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34
tools/testing/radix-tree/test.c
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@@ -151,6 +151,40 @@ void item_full_scan(struct radix_tree_root *root, unsigned long start,
assert(nfound == 0);
}
/* Use the same pattern as tag_pages_for_writeback() in mm/page-writeback.c */
int tag_tagged_items(struct radix_tree_root *root, pthread_mutex_t *lock,
unsigned long start, unsigned long end, unsigned batch,
unsigned iftag, unsigned thentag)
{
unsigned long tagged = 0;
struct radix_tree_iter iter;
void **slot;
if (batch == 0)
batch = 1;
if (lock)
pthread_mutex_lock(lock);
radix_tree_for_each_tagged(slot, root, &iter, start, iftag) {
if (iter.index > end)
break;
radix_tree_iter_tag_set(root, &iter, thentag);
tagged++;
if ((tagged % batch) != 0)
continue;
slot = radix_tree_iter_resume(slot, &iter);
if (lock) {
pthread_mutex_unlock(lock);
rcu_barrier();
pthread_mutex_lock(lock);
}
}
if (lock)
pthread_mutex_unlock(lock);
return tagged;
}
/* Use the same pattern as find_swap_entry() in mm/shmem.c */
unsigned long find_item(struct radix_tree_root *root, void *item)
{