Messages in this thread | | | Subject | Re: [PATCH v4] btrfs: Use larger zlib buffer for s390 hardware compression | From | Josef Bacik <> | Date | Wed, 8 Jan 2020 10:08:29 -0500 |
| |
On 1/8/20 5:51 AM, 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. > 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. > > Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
> --- > fs/btrfs/compression.c | 2 +- > fs/btrfs/zlib.c | 135 ++++++++++++++++++++++++++++++----------- > 2 files changed, 101 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..05615a1099db 100644 > --- a/fs/btrfs/zlib.c > +++ b/fs/btrfs/zlib.c > @@ -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 = kmalloc(PAGE_SIZE, GFP_KERNEL); > + 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; > - } > + if (workspace->strm.total_out > max_out) > + break; > } > workspace->strm.avail_in = 0; > - ret = zlib_deflate(&workspace->strm, Z_FINISH); > - zlib_deflateEnd(&workspace->strm); > - > - if (ret != Z_STREAM_END) { > - ret = -EIO; > - goto out; > + /* > + * 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); > + 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; > + }
Do we need zlib_deflateEnd() for the above error cases? Thanks,
Josef
| |