The patch titled
Subject: zsmalloc: micro-optimize zs_object_copy()
has been added to the -mm tree. Its filename is
zsmalloc-micro-optimize-zs_object_copy.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/zsmalloc-micro-optimize-zs_object_copy.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/zsmalloc-micro-optimize-zs_object_copy.patch
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------------------------------------------------------
From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Subject: zsmalloc: micro-optimize zs_object_copy()
A micro-optimization. Avoid additional branching and reduce (a bit)
registry pressure (f.e. s_off += size; d_off += size; may be calculated
twise: first for >= PAGE_SIZE check and later for offset update in "else"
clause).
/scripts/bloat-o-meter shows some improvement
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-10 (-10)
function old new delta
zs_object_copy 550 540 -10
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zsmalloc.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff -puN mm/zsmalloc.c~zsmalloc-micro-optimize-zs_object_copy mm/zsmalloc.c
--- a/mm/zsmalloc.c~zsmalloc-micro-optimize-zs_object_copy
+++ a/mm/zsmalloc.c
@@ -1537,28 +1537,27 @@ static void zs_object_copy(unsigned long
if (written == class->size)
break;
- if (s_off + size >= PAGE_SIZE) {
+ s_off += size;
+ s_size -= size;
+ d_off += size;
+ d_size -= size;
+
+ if (s_off >= PAGE_SIZE) {
kunmap_atomic(s_addr);
s_page = get_next_page(s_page);
BUG_ON(!s_page);
s_addr = kmap_atomic(s_page);
s_size = class->size - written;
s_off = 0;
- } else {
- s_off += size;
- s_size -= size;
}
- if (d_off + size >= PAGE_SIZE) {
+ if (d_off >= PAGE_SIZE) {
kunmap_atomic(d_addr);
d_page = get_next_page(d_page);
BUG_ON(!d_page);
d_addr = kmap_atomic(d_page);
d_size = class->size - written;
d_off = 0;
- } else {
- d_off += size;
- d_size -= size;
}
}
_
Patches currently in -mm which might be from sergey.senozhatsky@xxxxxxxxx are
zram-cosmetic-zram_attr_ro-code-formatting-tweak.patch
zram-use-idr-instead-of-zram_devices-array.patch
zram-factor-out-device-reset-from-reset_store.patch
zram-reorganize-code-layout.patch
zram-add-dynamic-device-add-remove-functionality.patch
zram-add-dynamic-device-add-remove-functionality-fix.patch
zram-remove-max_num_devices-limitation.patch
zram-report-every-added-and-removed-device.patch
zram-trivial-correct-flag-operations-comment.patch
zram-return-zram-device_id-value-from-zram_add.patch
zram-introduce-automatic-device_id-generation.patch
zram-introduce-automatic-device_id-generation-fix.patch
zram-do-not-let-user-enforce-new-device-dev_id.patch
zsmalloc-decouple-handle-and-object.patch
zsmalloc-factor-out-obj_.patch
zsmalloc-support-compaction.patch
zsmalloc-adjust-zs_almost_full.patch
zram-support-compaction.patch
zsmalloc-record-handle-in-page-private-for-huge-object.patch
zsmalloc-add-fullness-into-stat.patch
zsmalloc-zsmalloc-documentation.patch
zram-remove-num_migrated-device-attr.patch
zram-move-compact_store-to-sysfs-functions-area.patch
zram-use-generic-start-end-io-accounting.patch
zram-describe-device-attrs-in-documentation.patch
zram-export-new-io_stat-sysfs-attrs.patch
zram-export-new-mm_stat-sysfs-attrs.patch
zram-deprecate-zram-attrs-sysfs-nodes.patch
zsmalloc-remove-synchronize_rcu-from-zs_compact.patch
zsmalloc-remove-extra-cond_resched-in-__zs_compact.patch
zsmalloc-do-not-remap-dst-page-while-prepare-next-src-page.patch
zsmalloc-micro-optimize-zs_object_copy.patch
cpumask-dont-perform-while-loop-in-cpumask_next_and.patch
lib-lz4-pull-out-constant-tables.patch
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