106 lines
3.8 KiB
Diff
106 lines
3.8 KiB
Diff
From f8b15699d654c8ace6819287dcdd3c8e493b7f6c Mon Sep 17 00:00:00 2001
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From: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
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Date: Fri, 3 Jun 2022 13:47:34 -0300
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Subject: [PATCH] Reduce the scope for SW usage on length threshold
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When compressing/decompressing large amounts of data, the first call to
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deflate()/inflate() may not have data enough to pass the threshold,
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causing libnxz to fallback to software prematurely.
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We can only take that decision if the software indicates that all the
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input has been made available, i.e. when flush == Z_FINISH.
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Signed-off-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
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---
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lib/nx_deflate.c | 3 ++-
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lib/nx_inflate.c | 3 ++-
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lib/nx_zlib.h | 27 +++++++++++++++++++--------
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3 files changed, 23 insertions(+), 10 deletions(-)
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diff --git a/lib/nx_deflate.c b/lib/nx_deflate.c
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index f2d5222..05b3580 100644
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--- a/lib/nx_deflate.c
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+++ b/lib/nx_deflate.c
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@@ -1534,7 +1534,8 @@ int nx_deflate(z_streamp strm, int flush)
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return Z_STREAM_ERROR;
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/* check for sw deflate first */
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- if( (has_nx_state(strm)) && s->switchable && (0 == use_nx_deflate(strm))){
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+ if (has_nx_state(strm) && s->switchable
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+ && (0 == use_nx_deflate(strm, flush))) {
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/* Use software zlib, switch the sw and hw state */
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s = (nx_streamp) strm->state;
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s->switchable = 0; /* decided to use sw zlib and not switchable */
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diff --git a/lib/nx_inflate.c b/lib/nx_inflate.c
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index 6dac0ad..d59d5db 100644
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--- a/lib/nx_inflate.c
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+++ b/lib/nx_inflate.c
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@@ -289,7 +289,8 @@ int nx_inflate(z_streamp strm, int flush)
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if (s == NULL) return Z_STREAM_ERROR;
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/* check for sw deflate first*/
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- if(has_nx_state(strm) && s->switchable && (0 == use_nx_inflate(strm))){
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+ if (has_nx_state(strm) && s->switchable
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+ && (0 == use_nx_inflate(strm, flush))) {
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/*Use software zlib, switch the sw and hw state*/
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s = (nx_streamp) strm->state;
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s->switchable = 0; /* decided to use sw zlib and not switchable */
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diff --git a/lib/nx_zlib.h b/lib/nx_zlib.h
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index 7550c65..2c0bdb5 100644
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--- a/lib/nx_zlib.h
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+++ b/lib/nx_zlib.h
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@@ -341,7 +341,7 @@ static inline int has_nx_state(z_streamp strm)
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return (nx_state->magic1 == MAGIC1);
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}
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-static inline int use_nx_inflate(z_streamp strm)
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+static inline int use_nx_inflate(z_streamp strm, int flush)
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{
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uint64_t rnd;
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assert(strm != NULL);
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@@ -349,8 +349,13 @@ static inline int use_nx_inflate(z_streamp strm)
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if(nx_config.mode.inflate == GZIP_NX) return 1;
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if(nx_config.mode.inflate == GZIP_SW) return 0;
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- /* #1 Threshold */
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- if(strm->avail_in <= DECOMPRESS_THRESHOLD) return 0;
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+ /* #2 Length threshold
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+ Even when decompressing a large amount of data, the first call to
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+ inflate() may not have enough input. So, avoid switching to software
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+ decompression prematurely unless there is a guarantee that all the
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+ input has been provided, i.e. when using Z_FINISH. */
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+ if(flush == Z_FINISH && strm->avail_in <= DECOMPRESS_THRESHOLD)
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+ return 0;
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if(nx_config.mode.inflate == GZIP_AUTO) return 1;
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@@ -363,15 +368,21 @@ static inline int use_nx_inflate(z_streamp strm)
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}
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}
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-static inline int use_nx_deflate(z_streamp strm)
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+static inline int use_nx_deflate(z_streamp strm, int flush)
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{
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assert(strm != NULL);
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- if(nx_config.mode.deflate == GZIP_NX) return 1;
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- if(nx_config.mode.deflate == GZIP_SW) return 0;
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+ if(nx_config.mode.deflate == GZIP_NX) return 1;
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+ if(nx_config.mode.deflate == GZIP_SW) return 0;
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+
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+ /* #2 Length threshold
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+ Even when compressing a large amount of data, the first call to
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+ deflate() may not have enough input. So, avoid switching to software
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+ compression prematurely unless there is a guarantee that all the
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+ input has been provided, i.e. when using Z_FINISH. */
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+ if(flush == Z_FINISH && strm->avail_in <= COMPRESS_THRESHOLD)
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+ return 0;
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- /* #1 Threshold */
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- if(strm->avail_in <= COMPRESS_THRESHOLD) return 0;
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return 1;
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}
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--
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2.35.3
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