Commit 3fd396af authored by Mikhail Zaslonko's avatar Mikhail Zaslonko Committed by Linus Torvalds
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btrfs: use larger zlib buffer for s390 hardware compression 

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.

The data compressed with larger input buffers will still conform to zlib
standard and thus can be decompressed also on a systems that uses only
PAGE_SIZE buffer for btrfs zlib.

Link: http://lkml.kernel.org/r/20200108105103.29028-1-zaslonko@linux.ibm.com


Signed-off-by: default avatarMikhail Zaslonko <zaslonko@linux.ibm.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Eduard Shishkin <edward6@linux.ibm.com>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 803521b1

fs/btrfs/compression.c

+1 −1
Original line number Diff line number Diff line
@@ -1290,7 +1290,7 @@ 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);

fs/btrfs/zlib.c

+100 −35
Original line number Diff line number Diff line
@@ -20,9 +20,13 @@ 
#include <linux/refcount.h>

#include "compression.h"



/* workspace buffer size for s390 zlib hardware support */

#define ZLIB_DFLTCC_BUF_SIZE    (4 * PAGE_SIZE)



struct workspace {

	z_stream strm;

	char *buf;

	unsigned int buf_size;

	struct list_head list;

	int level;

};
@@ -61,7 +65,21 @@ struct list_head *zlib_alloc_workspace(unsigned int level) 
			zlib_inflate_workspacesize());

	workspace->strm.workspace = kvmalloc(workspacesize, GFP_KERNEL);

	workspace->level = level;

	workspace->buf = NULL;

	/*

	 * In case of s390 zlib hardware support, allocate lager workspace

	 * buffer. If allocator fails, fall back to a single page buffer.

	 */

	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;
@@ -85,6 +103,7 @@ 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 int 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 +121,6 @@ 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 +130,51 @@ 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) {

				int i;



				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;

				}

				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,

						       (unsigned long) workspace->buf_size);

		}



		ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);

		if (ret != Z_OK) {

			pr_debug("BTRFS: deflate in loop returned %d\n",
@@ -161,33 +216,43 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping, 
		/* we're all done */

		if (workspace->strm.total_in >= len)

			break;



		/* we've read in a full page, get a new one */

		if (workspace->strm.avail_in == 0) {

		if (workspace->strm.total_out > max_out)

			break;



			bytes_left = len - workspace->strm.total_in;

			kunmap(in_page);

			put_page(in_page);



			start += PAGE_SIZE;

			in_page = find_get_page(mapping,

						start >> PAGE_SHIFT);

			data_in = kmap(in_page);

			workspace->strm.avail_in = min(bytes_left,

							   PAGE_SIZE);

			workspace->strm.next_in = data_in;

		}

	}

	workspace->strm.avail_in = 0;

	/*

	 * Call deflate with Z_FINISH flush parameter providing more output

	 * space but no more input data, until it returns with Z_STREAM_END.

	 */

	while (ret != Z_STREAM_END) {

		ret = zlib_deflate(&workspace->strm, Z_FINISH);

		if (ret == Z_STREAM_END)

			break;

		if (ret != Z_OK && ret != Z_BUF_ERROR) {

			zlib_deflateEnd(&workspace->strm);



	if (ret != Z_STREAM_END) {

			ret = -EIO;

			goto out;

		} else if (workspace->strm.avail_out == 0) {

			/* get another page for the stream end */

			kunmap(out_page);

			if (nr_pages == nr_dest_pages) {

				out_page = NULL;

				ret = -E2BIG;

				goto out;

			}

			out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);

			if (out_page == NULL) {

				ret = -ENOMEM;

				goto out;

			}

			cpage_out = kmap(out_page);

			pages[nr_pages] = out_page;

			nr_pages++;

			workspace->strm.avail_out = PAGE_SIZE;

			workspace->strm.next_out = cpage_out;

		}

	}

	zlib_deflateEnd(&workspace->strm);



	if (workspace->strm.total_out >= workspace->strm.total_in) {

		ret = -E2BIG;
@@ -231,7 +296,7 @@ int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 


	workspace->strm.total_out = 0;

	workspace->strm.next_out = workspace->buf;

	workspace->strm.avail_out = PAGE_SIZE;

	workspace->strm.avail_out = workspace->buf_size;



	/* If it's deflate, and it's got no preset dictionary, then

	   we can tell zlib to skip the adler32 check. */
@@ -270,7 +335,7 @@ int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 
		}



		workspace->strm.next_out = workspace->buf;

		workspace->strm.avail_out = PAGE_SIZE;

		workspace->strm.avail_out = workspace->buf_size;



		if (workspace->strm.avail_in == 0) {

			unsigned long tmp;
@@ -320,7 +385,7 @@ int zlib_decompress(struct list_head *ws, unsigned char *data_in, 
	workspace->strm.total_in = 0;



	workspace->strm.next_out = workspace->buf;

	workspace->strm.avail_out = PAGE_SIZE;

	workspace->strm.avail_out = workspace->buf_size;

	workspace->strm.total_out = 0;

	/* If it's deflate, and it's got no preset dictionary, then

	   we can tell zlib to skip the adler32 check. */
@@ -364,7 +429,7 @@ int zlib_decompress(struct list_head *ws, unsigned char *data_in, 
			buf_offset = 0;



		bytes = min(PAGE_SIZE - pg_offset,

			    PAGE_SIZE - buf_offset);

			    PAGE_SIZE - (buf_offset % PAGE_SIZE));

		bytes = min(bytes, bytes_left);



		kaddr = kmap_atomic(dest_page);
@@ -375,7 +440,7 @@ int zlib_decompress(struct list_head *ws, unsigned char *data_in, 
		bytes_left -= bytes;

next:

		workspace->strm.next_out = workspace->buf;

		workspace->strm.avail_out = PAGE_SIZE;

		workspace->strm.avail_out = workspace->buf_size;

	}



	if (ret != Z_STREAM_END && bytes_left != 0)

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