v3: Use the aux struct as requested by Denys
v2: Add missing check on open
The performance and number of processes for a "depmod -a" with gzipped
modules was abysmal. This patch adds a fast path without fork for well-
behaved gzip files, benefiting all users of xmalloc_open_zipped_read_close.
"modinfo radeon.ko.gz", a single-file reader, got 30% faster.
"depmod -a", which used to fork over 800 times, got 20% faster. And of course
a whole lot less processes -> much saved RAM.
function old new delta
inflate_unzip_internal 2304 2521 +217
xmalloc_open_zipped_read_close 73 201 +128
unpack_gz_stream 567 570 +3
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/0 up/down: 348/0) Total: 348 bytes
--
http://www.fastmail.com - Does exactly what it says on the tin
From 5ad6804ed4485eae176da45524ea848a00b11929 Mon Sep 17 00:00:00 2001
From: Lauri Kasanen <cur...@operamail.com>
Date: Sun, 30 Nov 2014 21:37:10 +0200
Subject: [PATCH] Add a gzip fastpath for the xmalloc readers, v3
v3: Use the aux struct as requested by Denys
v2: Add missing check on open
The performance and number of processes for a "depmod -a" with gzipped
modules was abysmal. This patch adds a fast path without fork for well-
behaved gzip files, benefiting all users of xmalloc_open_zipped_read_close.
"modinfo radeon.ko.gz", a single-file reader, got 30% faster.
"depmod -a", which used to fork over 800 times, got 20% faster. And of course
a whole lot less processes -> much saved RAM.
function old new delta
inflate_unzip_internal 2304 2521 +217
xmalloc_open_zipped_read_close 73 201 +128
unpack_gz_stream 567 570 +3
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/0 up/down: 348/0) Total: 348 bytes
Signed-off-by: Lauri Kasanen <cur...@operamail.com>
---
archival/libarchive/decompress_gunzip.c | 38 ++++++++++++++++++++++++++++-----
archival/libarchive/open_transformer.c | 31 ++++++++++++++++++++++++++-
include/bb_archive.h | 2 ++
3 files changed, 65 insertions(+), 6 deletions(-)
diff --git a/archival/libarchive/decompress_gunzip.c
b/archival/libarchive/decompress_gunzip.c
index 7c6f38e..938d21f 100644
--- a/archival/libarchive/decompress_gunzip.c
+++ b/archival/libarchive/decompress_gunzip.c
@@ -971,10 +971,11 @@ static int inflate_get_next_window(STATE_PARAM_ONLY)
/* Called from unpack_gz_stream() and inflate_unzip() */
static IF_DESKTOP(long long) int
-inflate_unzip_internal(STATE_PARAM int in, int out)
+inflate_unzip_internal(STATE_PARAM transformer_aux_data_t *aux, int in, int
out)
{
IF_DESKTOP(long long) int n = 0;
ssize_t nwrote;
+ size_t bufsize = 0;
/* Allocate all global buffers (for DYN_ALLOC option) */
gunzip_window = xmalloc(GUNZIP_WSIZE);
@@ -1002,16 +1003,43 @@ inflate_unzip_internal(STATE_PARAM int in, int out)
while (1) {
int r = inflate_get_next_window(PASS_STATE_ONLY);
- nwrote = full_write(out, gunzip_window, gunzip_outbuf_count);
+
+ if (aux->mem_output_size) {
+ nwrote = gunzip_outbuf_count;
+ if (gunzip_outbuf_count + n > bufsize) {
+ // increase by four blocks each time
+ const size_t newsize = bufsize + 4 *
gunzip_outbuf_count + 1;
+ aux->mem_output_buf =
xrealloc(aux->mem_output_buf, newsize);
+ bufsize = newsize;
+ }
+
+ if (bufsize > aux->mem_output_size) {
+ free(aux->mem_output_buf);
+ aux->mem_output_buf = NULL;
+ n = -1;
+ goto ret;
+ }
+
+ memcpy(aux->mem_output_buf + n, gunzip_window,
gunzip_outbuf_count);
+ } else {
+ nwrote = full_write(out, gunzip_window,
gunzip_outbuf_count);
+ }
if (nwrote != (ssize_t)gunzip_outbuf_count) {
bb_perror_msg("write");
n = -1;
goto ret;
}
- IF_DESKTOP(n += nwrote;)
+ n += nwrote;
if (r == 0) break;
}
+ /* Final realloc, plus zero byte */
+ if (aux->mem_output_size) {
+ aux->mem_output_buf = xrealloc(aux->mem_output_buf, n + 1);
+ aux->mem_output_size = n;
+ aux->mem_output_buf[n] = '\0';
+ }
+
/* Store unused bytes in a global buffer so calling applets can access
it */
if (gunzip_bk >= 8) {
/* Undo too much lookahead. The next read will be byte aligned
@@ -1045,7 +1073,7 @@ inflate_unzip(transformer_aux_data_t *aux, int in, int
out)
// bytebuffer_max = 0x8000;
bytebuffer_offset = 4;
bytebuffer = xmalloc(bytebuffer_max);
- n = inflate_unzip_internal(PASS_STATE in, out);
+ n = inflate_unzip_internal(PASS_STATE aux, in, out);
free(bytebuffer);
aux->crc32 = gunzip_crc;
@@ -1224,7 +1252,7 @@ unpack_gz_stream(transformer_aux_data_t *aux, int src_fd,
int dst_fd)
goto ret;
}
- n = inflate_unzip_internal(PASS_STATE src_fd, dst_fd);
+ n = inflate_unzip_internal(PASS_STATE aux, src_fd, dst_fd);
if (n < 0) {
total = -1;
goto ret;
diff --git a/archival/libarchive/open_transformer.c
b/archival/libarchive/open_transformer.c
index 1986630..ad9dce5 100644
--- a/archival/libarchive/open_transformer.c
+++ b/archival/libarchive/open_transformer.c
@@ -211,7 +211,36 @@ int FAST_FUNC open_zipped(const char *fname, int
fail_if_not_compressed)
void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t
*maxsz_p)
{
int fd;
- char *image;
+ char *image = NULL;
+
+ /* Fast path for well-behaved gzip files, avoiding forks. */
+ if (ENABLE_FEATURE_SEAMLESS_GZ && ENABLE_DESKTOP && BB_MMU) {
+ uint16_t magic;
+ fd = open(fname, O_RDONLY);
+ if (fd < 0)
+ return NULL;
+
+ xread(fd, &magic, 2);
+
+ if (magic == GZIP_MAGIC) {
+ transformer_aux_data_t aux;
+ init_transformer_aux_data(&aux);
+
+ /* In-memory decompression instead of the usual fork */
+ aux.mem_output_size = *maxsz_p;
+
+ unpack_gz_stream(&aux, fd, -1);
+
+ if (aux.mem_output_buf) {
+ image = aux.mem_output_buf;
+ *maxsz_p = aux.mem_output_size;
+ }
+ }
+
+ close(fd);
+ if (image)
+ return image;
+ }
fd = open_zipped(fname, /*fail_if_not_compressed:*/ 0);
if (fd < 0)
diff --git a/include/bb_archive.h b/include/bb_archive.h
index b82cfd8..6b19413 100644
--- a/include/bb_archive.h
+++ b/include/bb_archive.h
@@ -209,6 +209,8 @@ typedef struct transformer_aux_data_t {
off_t bytes_in; /* used in unzip code only: needs to know packed
size */
uint32_t crc32;
time_t mtime; /* gunzip code may set this on exit */
+ size_t mem_output_size; /* if non-zero, decompress to RAM instead of
fd */
+ char *mem_output_buf;
} transformer_aux_data_t;
void init_transformer_aux_data(transformer_aux_data_t *aux) FAST_FUNC;
--
1.8.3.1
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