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Message-Id: <20240930140424.4049195-1-guochunhai@vivo.com>
Date: Mon, 30 Sep 2024 08:04:24 -0600
From: Chunhai Guo <guochunhai@...o.com>
To: xiang@...nel.org
Cc: chao@...nel.org,
huyue2@...lpad.com,
jefflexu@...ux.alibaba.com,
dhavale@...gle.com,
linux-erofs@...ts.ozlabs.org,
linux-kernel@...r.kernel.org,
Chunhai Guo <guochunhai@...o.com>
Subject: [PATCH] erofs: free pcluster right after decompression if possible
Once a pcluster is fully decompressed and there are no attached cached
pages, 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 95% 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 2.1 GB partition on ARM64 Android devices
running the 5.15 kernel with an 8-core CPU and 8GB of memory.
1. The reduction in calls to erofs_shrink_scan():
+-----------------+-----------+----------+---------+
| | w/o patch | w/ patch | diff |
+-----------------+-----------+----------+---------+
| Average (times) | 3152 | 160 | -94.92% |
+-----------------+-----------+----------+---------+
2. The reduction in memory released by erofs_shrink_scan():
+-----------------+-----------+----------+---------+
| | w/o patch | w/ patch | diff |
+-----------------+-----------+----------+---------+
| Average (Byte) | 44503200 | 2293760 | -94.84% |
+-----------------+-----------+----------+---------+
Signed-off-by: Chunhai Guo <guochunhai@...o.com>
---
fs/erofs/internal.h | 3 ++-
fs/erofs/zdata.c | 14 ++++++++---
fs/erofs/zutil.c | 58 +++++++++++++++++++++++++++++----------------
3 files changed, 51 insertions(+), 24 deletions(-)
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 4efd578d7c62..17b04bfd743f 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -456,7 +456,8 @@ static inline void erofs_pagepool_add(struct page **pagepool, struct page *page)
void erofs_release_pages(struct page **pagepool);
#ifdef CONFIG_EROFS_FS_ZIP
-void erofs_workgroup_put(struct erofs_workgroup *grp);
+void erofs_workgroup_put(struct erofs_sb_info *sbi, struct erofs_workgroup *grp,
+ bool can_released);
struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
pgoff_t index);
struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb,
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 8936790618c6..656fd65aec33 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -888,7 +888,7 @@ 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)
- erofs_workgroup_put(&pcl->obj);
+ erofs_workgroup_put(EROFS_I_SB(fe->inode), &pcl->obj, false);
fe->pcl = NULL;
}
@@ -1046,6 +1046,9 @@ struct z_erofs_decompress_backend {
struct list_head decompressed_secondary_bvecs;
struct page **pagepool;
unsigned int onstack_used, nr_pages;
+
+ /* whether the pcluster can be released after its decompression */
+ bool try_free;
};
struct z_erofs_bvec_item {
@@ -1244,12 +1247,15 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
WRITE_ONCE(pcl->compressed_bvecs[0].page, NULL);
put_page(page);
} else {
+ be->try_free = true;
/* 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)))
+ erofs_folio_is_managed(sbi, page_folio(page))) {
+ be->try_free = false;
continue;
+ }
(void)z_erofs_put_shortlivedpage(be->pagepool, page);
WRITE_ONCE(pcl->compressed_bvecs[i].page, NULL);
}
@@ -1285,6 +1291,7 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
if (be->decompressed_pages != be->onstack_pages)
kvfree(be->decompressed_pages);
+ be->try_free = be->try_free && !pcl->partial;
pcl->length = 0;
pcl->partial = true;
pcl->multibases = false;
@@ -1320,7 +1327,8 @@ static int z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
if (z_erofs_is_inline_pcluster(be.pcl))
z_erofs_free_pcluster(be.pcl);
else
- erofs_workgroup_put(&be.pcl->obj);
+ erofs_workgroup_put(EROFS_SB(io->sb), &be.pcl->obj,
+ be.try_free);
}
return err;
}
diff --git a/fs/erofs/zutil.c b/fs/erofs/zutil.c
index 37afe2024840..cf59ba6a2322 100644
--- a/fs/erofs/zutil.c
+++ b/fs/erofs/zutil.c
@@ -285,26 +285,11 @@ static void __erofs_workgroup_free(struct erofs_workgroup *grp)
erofs_workgroup_free_rcu(grp);
}
-void erofs_workgroup_put(struct erofs_workgroup *grp)
-{
- if (lockref_put_or_lock(&grp->lockref))
- return;
-
- DBG_BUGON(__lockref_is_dead(&grp->lockref));
- if (grp->lockref.count == 1)
- atomic_long_inc(&erofs_global_shrink_cnt);
- --grp->lockref.count;
- spin_unlock(&grp->lockref.lock);
-}
-
-static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
+static bool erofs_prepare_to_release_workgroup(struct erofs_sb_info *sbi,
struct erofs_workgroup *grp)
{
- int free = false;
-
- spin_lock(&grp->lockref.lock);
if (grp->lockref.count)
- goto out;
+ return false;
/*
* Note that all cached pages should be detached before deleted from
@@ -312,7 +297,7 @@ static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
* the orphan old workgroup when the new one is available in the tree.
*/
if (erofs_try_to_free_all_cached_folios(sbi, grp))
- goto out;
+ return false;
/*
* It's impossible to fail after the workgroup is freezed,
@@ -322,14 +307,47 @@ static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
DBG_BUGON(__xa_erase(&sbi->managed_pslots, grp->index) != grp);
lockref_mark_dead(&grp->lockref);
- free = true;
-out:
+ return true;
+}
+
+static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
+ struct erofs_workgroup *grp)
+{
+ bool free = false;
+
+ /* Using trylock to avoid deadlock with erofs_workgroup_put() */
+ if (!spin_trylock(&grp->lockref.lock))
+ return free;
+ free = erofs_prepare_to_release_workgroup(sbi, grp);
spin_unlock(&grp->lockref.lock);
if (free)
__erofs_workgroup_free(grp);
return free;
}
+void erofs_workgroup_put(struct erofs_sb_info *sbi, struct erofs_workgroup *grp,
+ bool try_free)
+{
+ bool free = false;
+
+ if (lockref_put_or_lock(&grp->lockref))
+ return;
+
+ DBG_BUGON(__lockref_is_dead(&grp->lockref));
+ if (--grp->lockref.count == 0) {
+ atomic_long_inc(&erofs_global_shrink_cnt);
+
+ if (try_free) {
+ xa_lock(&sbi->managed_pslots);
+ free = erofs_prepare_to_release_workgroup(sbi, grp);
+ xa_unlock(&sbi->managed_pslots);
+ }
+ }
+ spin_unlock(&grp->lockref.lock);
+ if (free)
+ __erofs_workgroup_free(grp);
+}
+
static unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
unsigned long nr_shrink)
{
--
2.25.1
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