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erofs: free pclusters if no cached folio is attached

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Once a pcluster is fully decompressed and there are no attached cached
folios, its corresponding `struct z_erofs_pcluster` will be freed. This
will significantly reduce the frequency of calls to erofs_shrink_scan()
and the memory allocated for `struct z_erofs_pcluster`.

The tables below show approximately a 96% reduction in the calls to
erofs_shrink_scan() and in the memory allocated for `struct
z_erofs_pcluster` after applying this patch. The results were obtained
by performing a test to copy a 4.1GB partition on ARM64 Android devices
running the 6.6 kernel with an 8-core CPU and 12GB of memory.

1. The reduction in calls to erofs_shrink_scan():
+-----------------+-----------+----------+---------+
|                 | w/o patch | w/ patch |  diff   |
+-----------------+-----------+----------+---------+
| Average (times) |   11390   |   390    | -96.57% |
+-----------------+-----------+----------+---------+

2. The reduction in memory released by erofs_shrink_scan():
+-----------------+-----------+----------+---------+
|                 | w/o patch | w/ patch |  diff   |
+-----------------+-----------+----------+---------+
| Average (Byte)  | 133612656 | 4434552  | -96.68% |
+-----------------+-----------+----------+---------+

Signed-off-by: Chunhai Guo <guochunhai@vivo.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20241112043235.546164-1-guochunhai@vivo.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
This commit is contained in:
Chunhai Guo 2024-11-11 21:32:35 -07:00 committed by Gao Xiang
parent bf1aa03980
commit f5ad9f9a60
1 changed files with 38 additions and 19 deletions
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57
fs/erofs/zdata.c
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@ -885,14 +885,11 @@ static void z_erofs_rcu_callback(struct rcu_head *head)
struct z_erofs_pcluster, rcu));
}
static bool erofs_try_to_release_pcluster(struct erofs_sb_info *sbi,
static bool __erofs_try_to_release_pcluster(struct erofs_sb_info *sbi,
struct z_erofs_pcluster *pcl)
{
int free = false;
spin_lock(&pcl->lockref.lock);
if (pcl->lockref.count)
goto out;
return false;
/*
* Note that all cached folios should be detached before deleted from
@ -900,7 +897,7 @@ static bool erofs_try_to_release_pcluster(struct erofs_sb_info *sbi,
* orphan old pcluster when the new one is available in the tree.
*/
if (erofs_try_to_free_all_cached_folios(sbi, pcl))
goto out;
return false;
/*
* It's impossible to fail after the pcluster is freezed, but in order
@ -909,8 +906,16 @@ static bool erofs_try_to_release_pcluster(struct erofs_sb_info *sbi,
DBG_BUGON(__xa_erase(&sbi->managed_pslots, pcl->index) != pcl);
lockref_mark_dead(&pcl->lockref);
free = true;
out:
return true;
}
static bool erofs_try_to_release_pcluster(struct erofs_sb_info *sbi,
struct z_erofs_pcluster *pcl)
{
bool free;
spin_lock(&pcl->lockref.lock);
free = __erofs_try_to_release_pcluster(sbi, pcl);
spin_unlock(&pcl->lockref.lock);
if (free) {
atomic_long_dec(&erofs_global_shrink_cnt);
@ -942,16 +947,25 @@ unsigned long z_erofs_shrink_scan(struct erofs_sb_info *sbi,
return freed;
}
static void z_erofs_put_pcluster(struct z_erofs_pcluster *pcl)
static void z_erofs_put_pcluster(struct erofs_sb_info *sbi,
struct z_erofs_pcluster *pcl, bool try_free)
{
bool free = false;
if (lockref_put_or_lock(&pcl->lockref))
return;
DBG_BUGON(__lockref_is_dead(&pcl->lockref));
if (pcl->lockref.count == 1)
atomic_long_inc(&erofs_global_shrink_cnt);
--pcl->lockref.count;
if (!--pcl->lockref.count) {
if (try_free && xa_trylock(&sbi->managed_pslots)) {
free = __erofs_try_to_release_pcluster(sbi, pcl);
xa_unlock(&sbi->managed_pslots);
}
atomic_long_add(!free, &erofs_global_shrink_cnt);
}
spin_unlock(&pcl->lockref.lock);
if (free)
call_rcu(&pcl->rcu, z_erofs_rcu_callback);
}
static void z_erofs_pcluster_end(struct z_erofs_decompress_frontend *fe)
@ -972,7 +986,7 @@ static void z_erofs_pcluster_end(struct z_erofs_decompress_frontend *fe)
* any longer if the pcluster isn't hosted by ourselves.
*/
if (fe->mode < Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE)
z_erofs_put_pcluster(pcl);
z_erofs_put_pcluster(EROFS_I_SB(fe->inode), pcl, false);
fe->pcl = NULL;
}
@ -1274,6 +1288,7 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
int i, j, jtop, err2;
struct page *page;
bool overlapped;
bool try_free = true;
mutex_lock(&pcl->lock);
be->nr_pages = PAGE_ALIGN(pcl->length + pcl->pageofs_out) >> PAGE_SHIFT;
@ -1331,9 +1346,12 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
/* managed folios are still left in compressed_bvecs[] */
for (i = 0; i < pclusterpages; ++i) {
page = be->compressed_pages[i];
if (!page ||
erofs_folio_is_managed(sbi, page_folio(page)))
if (!page)
continue;
if (erofs_folio_is_managed(sbi, page_folio(page))) {
try_free = false;
continue;
}
(void)z_erofs_put_shortlivedpage(be->pagepool, page);
WRITE_ONCE(pcl->compressed_bvecs[i].page, NULL);
}
@ -1379,6 +1397,11 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
/* pcluster lock MUST be taken before the following line */
WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_NIL);
mutex_unlock(&pcl->lock);
if (z_erofs_is_inline_pcluster(pcl))
z_erofs_free_pcluster(pcl);
else
z_erofs_put_pcluster(sbi, pcl, try_free);
return err;
}
@ -1401,10 +1424,6 @@ static int z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
owned = READ_ONCE(be.pcl->next);
err = z_erofs_decompress_pcluster(&be, err) ?: err;
if (z_erofs_is_inline_pcluster(be.pcl))
z_erofs_free_pcluster(be.pcl);
else
z_erofs_put_pcluster(be.pcl);
}
return err;
}