On 1/3/20 5:33 PM, Mikhail Zaslonko wrote:
In order to benefit from s390 zlib hardware compression support,
increase the btrfs zlib workspace buffer size from 1 to 4 pages (if
s390 zlib hardware support is enabled on the machine). This brings up
to 60% better performance in hardware on s390 compared to the PAGE_SIZE
buffer and much more compared to the software zlib processing in btrfs.
In case of memory pressure fall back to a single page buffer during
workspace allocation.
Signed-off-by: Mikhail Zaslonko <zaslonko@xxxxxxxxxxxxx>
---
fs/btrfs/compression.c | 2 +-
fs/btrfs/zlib.c | 128 ++++++++++++++++++++++++++++++-----------
2 files changed, 94 insertions(+), 36 deletions(-)
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index ee834ef7beb4..6bd0e75a822c 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -1285,7 +1285,7 @@ int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
/* copy bytes from the working buffer into the pages */
while (working_bytes > 0) {
bytes = min_t(unsigned long, bvec.bv_len,
- PAGE_SIZE - buf_offset);
+ PAGE_SIZE - (buf_offset % PAGE_SIZE));
bytes = min(bytes, working_bytes);
kaddr = kmap_atomic(bvec.bv_page);
diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index a6c90a003c12..159486801631 100644
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -20,9 +20,12 @@
#include <linux/refcount.h>
#include "compression.h"
+#define ZLIB_DFLTCC_BUF_SIZE (4 * PAGE_SIZE)
+
struct workspace {
z_stream strm;
char *buf;
+ unsigned long buf_size;
struct list_head list;
int level;
};
@@ -61,7 +64,17 @@ struct list_head *zlib_alloc_workspace(unsigned int level)
zlib_inflate_workspacesize());
workspace->strm.workspace = kvmalloc(workspacesize, GFP_KERNEL);
workspace->level = level;
- workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ workspace->buf = NULL;
+ if (zlib_deflate_dfltcc_enabled()) {
+ workspace->buf = kmalloc(ZLIB_DFLTCC_BUF_SIZE,
+ __GFP_NOMEMALLOC | __GFP_NORETRY |
+ __GFP_NOWARN | GFP_NOIO);
+ workspace->buf_size = ZLIB_DFLTCC_BUF_SIZE;
+ }
+ if (!workspace->buf) {
+ workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ workspace->buf_size = PAGE_SIZE;
+ }
if (!workspace->strm.workspace || !workspace->buf)
goto fail;
@@ -78,6 +91,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
unsigned long *total_in, unsigned long *total_out)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
+ int i;
int ret;
char *data_in;
char *cpage_out;
@@ -85,6 +99,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
struct page *in_page = NULL;
struct page *out_page = NULL;
unsigned long bytes_left;
+ unsigned long in_buf_pages;
unsigned long len = *total_out;
unsigned long nr_dest_pages = *out_pages;
const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
@@ -102,9 +117,6 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
workspace->strm.total_in = 0;
workspace->strm.total_out = 0;
- in_page = find_get_page(mapping, start >> PAGE_SHIFT);
- data_in = kmap(in_page);
-
out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
if (out_page == NULL) {
ret = -ENOMEM;
@@ -114,12 +126,48 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
pages[0] = out_page;
nr_pages = 1;
- workspace->strm.next_in = data_in;
+ workspace->strm.next_in = workspace->buf;
+ workspace->strm.avail_in = 0;
workspace->strm.next_out = cpage_out;
workspace->strm.avail_out = PAGE_SIZE;
- workspace->strm.avail_in = min(len, PAGE_SIZE);
while (workspace->strm.total_in < len) {
+ /* get next input pages and copy the contents to
+ * the workspace buffer if required
+ */
+ if (workspace->strm.avail_in == 0) {
+ bytes_left = len - workspace->strm.total_in;
+ in_buf_pages = min(DIV_ROUND_UP(bytes_left, PAGE_SIZE),
+ workspace->buf_size / PAGE_SIZE);
+ if (in_buf_pages > 1) {
+ for (i = 0; i < in_buf_pages; i++) {
+ if (in_page) {
+ kunmap(in_page);
+ put_page(in_page);
+ }
+ in_page = find_get_page(mapping,
+ start >> PAGE_SHIFT);
+ data_in = kmap(in_page);
+ memcpy(workspace->buf + i*PAGE_SIZE,
+ data_in, PAGE_SIZE);
+ start += PAGE_SIZE;
+ }
Is there a reason to leave the last in_page mapped here? I realize we'll clean
it up further down, but since we're copying everything into the buf anyway why
not just map->copy->unmap for everything?
+ workspace->strm.next_in = workspace->buf;
+ } else {
+ if (in_page) {
+ kunmap(in_page);
+ put_page(in_page);
+ }
+ in_page = find_get_page(mapping,
+ start >> PAGE_SHIFT);
+ data_in = kmap(in_page);
+ start += PAGE_SIZE;
+ workspace->strm.next_in = data_in;
+ }
+ workspace->strm.avail_in = min(bytes_left,
+ workspace->buf_size);
+ }
+
ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);
if (ret != Z_OK) {
pr_debug("BTRFS: deflate in loop returned %d\n",
@@ -136,6 +184,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
ret = -E2BIG;
goto out;
}
+
Extra newline. Thanks,
Josef
