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Subject[PATCH v3 3/8] staging: erofs: move per-CPU buffers implementation to utils.c
Date
From: Gao Xiang <gaoxiang25@huawei.com>

This patch moves per-CPU buffers to utils.c in order for
the upcoming generic decompression framework to use it.

Note that I tried to use generic per-CPU buffer or
per-CPU page approaches to clean up further, but obvious
performanace regression (about 2% for sequential read) was
observed.

Therefore let's leave it as it is instead, just move
to utils.c and I'll try to dig into the root cause later.

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
change log v3:
- handle error code if returned by erofs_get_pcpubuf() pointed out by Chao.

drivers/staging/erofs/internal.h | 26 +++++++++++++++++++
drivers/staging/erofs/unzip_vle.c | 5 ++--
drivers/staging/erofs/unzip_vle.h | 4 +--
drivers/staging/erofs/unzip_vle_lz4.c | 37 +++++++++++----------------
drivers/staging/erofs/utils.c | 12 +++++++++
5 files changed, 56 insertions(+), 28 deletions(-)

diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index f3063b13c117..dcbe6f7f5dae 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -321,6 +321,16 @@ static inline void z_erofs_exit_zip_subsystem(void) {}

/* page count of a compressed cluster */
#define erofs_clusterpages(sbi) ((1 << (sbi)->clusterbits) / PAGE_SIZE)
+#define Z_EROFS_NR_INLINE_PAGEVECS 3
+
+#if (Z_EROFS_CLUSTER_MAX_PAGES > Z_EROFS_NR_INLINE_PAGEVECS)
+#define EROFS_PCPUBUF_NR_PAGES Z_EROFS_CLUSTER_MAX_PAGES
+#else
+#define EROFS_PCPUBUF_NR_PAGES Z_EROFS_NR_INLINE_PAGEVECS
+#endif
+
+#else
+#define EROFS_PCPUBUF_NR_PAGES 0
#endif

typedef u64 erofs_off_t;
@@ -608,6 +618,22 @@ static inline void erofs_vunmap(const void *mem, unsigned int count)
extern struct shrinker erofs_shrinker_info;

struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp);
+
+#if (EROFS_PCPUBUF_NR_PAGES > 0)
+void *erofs_get_pcpubuf(unsigned int pagenr);
+#define erofs_put_pcpubuf(buf) do { \
+ (void)&(buf); \
+ preempt_enable(); \
+} while (0)
+#else
+static inline void *erofs_get_pcpubuf(unsigned int pagenr)
+{
+ return ERR_PTR(-ENOTSUPP);
+}
+
+#define erofs_put_pcpubuf(buf) do {} while (0)
+#endif
+
void erofs_register_super(struct super_block *sb);
void erofs_unregister_super(struct super_block *sb);

diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
index 8aea938172df..08f2d4302ecb 100644
--- a/drivers/staging/erofs/unzip_vle.c
+++ b/drivers/staging/erofs/unzip_vle.c
@@ -552,8 +552,7 @@ static int z_erofs_vle_work_iter_begin(struct z_erofs_vle_work_builder *builder,
if (IS_ERR(work))
return PTR_ERR(work);
got_it:
- z_erofs_pagevec_ctor_init(&builder->vector,
- Z_EROFS_VLE_INLINE_PAGEVECS,
+ z_erofs_pagevec_ctor_init(&builder->vector, Z_EROFS_NR_INLINE_PAGEVECS,
work->pagevec, work->vcnt);

if (builder->role >= Z_EROFS_VLE_WORK_PRIMARY) {
@@ -936,7 +935,7 @@ static int z_erofs_vle_unzip(struct super_block *sb,
for (i = 0; i < nr_pages; ++i)
pages[i] = NULL;

- z_erofs_pagevec_ctor_init(&ctor, Z_EROFS_VLE_INLINE_PAGEVECS,
+ z_erofs_pagevec_ctor_init(&ctor, Z_EROFS_NR_INLINE_PAGEVECS,
work->pagevec, 0);

for (i = 0; i < work->vcnt; ++i) {
diff --git a/drivers/staging/erofs/unzip_vle.h b/drivers/staging/erofs/unzip_vle.h
index 902e67d04029..9c53009700cf 100644
--- a/drivers/staging/erofs/unzip_vle.h
+++ b/drivers/staging/erofs/unzip_vle.h
@@ -44,8 +44,6 @@ static inline bool z_erofs_gather_if_stagingpage(struct list_head *page_pool,
*
*/

-#define Z_EROFS_VLE_INLINE_PAGEVECS 3
-
struct z_erofs_vle_work {
struct mutex lock;

@@ -58,7 +56,7 @@ struct z_erofs_vle_work {

union {
/* L: pagevec */
- erofs_vtptr_t pagevec[Z_EROFS_VLE_INLINE_PAGEVECS];
+ erofs_vtptr_t pagevec[Z_EROFS_NR_INLINE_PAGEVECS];
struct rcu_head rcu;
};
};
diff --git a/drivers/staging/erofs/unzip_vle_lz4.c b/drivers/staging/erofs/unzip_vle_lz4.c
index 0daac9b984a8..02e694d9288d 100644
--- a/drivers/staging/erofs/unzip_vle_lz4.c
+++ b/drivers/staging/erofs/unzip_vle_lz4.c
@@ -34,16 +34,6 @@ static int z_erofs_unzip_lz4(void *in, void *out, size_t inlen, size_t outlen)
return -EIO;
}

-#if Z_EROFS_CLUSTER_MAX_PAGES > Z_EROFS_VLE_INLINE_PAGEVECS
-#define EROFS_PERCPU_NR_PAGES Z_EROFS_CLUSTER_MAX_PAGES
-#else
-#define EROFS_PERCPU_NR_PAGES Z_EROFS_VLE_INLINE_PAGEVECS
-#endif
-
-static struct {
- char data[PAGE_SIZE * EROFS_PERCPU_NR_PAGES];
-} erofs_pcpubuf[NR_CPUS];
-
int z_erofs_vle_plain_copy(struct page **compressed_pages,
unsigned int clusterpages,
struct page **pages,
@@ -56,8 +46,9 @@ int z_erofs_vle_plain_copy(struct page **compressed_pages,
char *percpu_data;
bool mirrored[Z_EROFS_CLUSTER_MAX_PAGES] = { 0 };

- preempt_disable();
- percpu_data = erofs_pcpubuf[smp_processor_id()].data;
+ percpu_data = erofs_get_pcpubuf(0);
+ if (IS_ERR(percpu_data))
+ return PTR_ERR(percpu_data);

j = 0;
for (i = 0; i < nr_pages; j = i++) {
@@ -117,7 +108,7 @@ int z_erofs_vle_plain_copy(struct page **compressed_pages,
if (src && !mirrored[j])
kunmap_atomic(src);

- preempt_enable();
+ erofs_put_pcpubuf(percpu_data);
return 0;
}

@@ -131,7 +122,7 @@ int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages,
unsigned int nr_pages, i, j;
int ret;

- if (outlen + pageofs > EROFS_PERCPU_NR_PAGES * PAGE_SIZE)
+ if (outlen + pageofs > EROFS_PCPUBUF_NR_PAGES * PAGE_SIZE)
return -ENOTSUPP;

nr_pages = DIV_ROUND_UP(outlen + pageofs, PAGE_SIZE);
@@ -144,8 +135,9 @@ int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages,
return -ENOMEM;
}

- preempt_disable();
- vout = erofs_pcpubuf[smp_processor_id()].data;
+ vout = erofs_get_pcpubuf(0);
+ if (IS_ERR(vout))
+ return PTR_ERR(vout);

ret = z_erofs_unzip_lz4(vin, vout + pageofs,
clusterpages * PAGE_SIZE, outlen);
@@ -174,7 +166,7 @@ int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages,
}

out:
- preempt_enable();
+ erofs_put_pcpubuf(vout);

if (clusterpages == 1)
kunmap_atomic(vin);
@@ -196,8 +188,9 @@ int z_erofs_vle_unzip_vmap(struct page **compressed_pages,
int ret;

if (overlapped) {
- preempt_disable();
- vin = erofs_pcpubuf[smp_processor_id()].data;
+ vin = erofs_get_pcpubuf(0);
+ if (IS_ERR(vin))
+ return PTR_ERR(vin);

for (i = 0; i < clusterpages; ++i) {
void *t = kmap_atomic(compressed_pages[i]);
@@ -216,13 +209,13 @@ int z_erofs_vle_unzip_vmap(struct page **compressed_pages,
if (ret > 0)
ret = 0;

- if (!overlapped) {
+ if (overlapped) {
+ erofs_put_pcpubuf(vin);
+ } else {
if (clusterpages == 1)
kunmap_atomic(vin);
else
erofs_vunmap(vin, clusterpages);
- } else {
- preempt_enable();
}
return ret;
}
diff --git a/drivers/staging/erofs/utils.c b/drivers/staging/erofs/utils.c
index 3e7d30b6de1d..4bbd3bf34acd 100644
--- a/drivers/staging/erofs/utils.c
+++ b/drivers/staging/erofs/utils.c
@@ -27,6 +27,18 @@ struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp)
return page;
}

+#if (EROFS_PCPUBUF_NR_PAGES > 0)
+static struct {
+ u8 data[PAGE_SIZE * EROFS_PCPUBUF_NR_PAGES];
+} ____cacheline_aligned_in_smp erofs_pcpubuf[NR_CPUS];
+
+void *erofs_get_pcpubuf(unsigned int pagenr)
+{
+ preempt_disable();
+ return &erofs_pcpubuf[smp_processor_id()].data[pagenr * PAGE_SIZE];
+}
+#endif
+
/* global shrink count (for all mounted EROFS instances) */
static atomic_long_t erofs_global_shrink_cnt;

--
2.17.1
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