From 28389c230c822a0c1adbdfa2dd88ae7f51072903 Mon Sep 17 00:00:00 2001
From: Bryan Stillwell <bstillwell@godaddy.com>
Date: Fri, 11 Sep 2020 16:51:19 -0600
Subject: [PATCH 1/2] compressor: Add a config option to specify Zstd
 compression level

Add a new configuration item called 'compressor_zstd_level' so that the
Zstandard compression level can be tuned to the workload on a cluster.

Fixes: https://tracker.ceph.com/issues/47422
Signed-off-by: Bryan Stillwell <bstillwell@godaddy.com>
---
 src/common/legacy_config_opts.h             | 1 +
 src/common/options.cc                       | 4 ++++
 src/compressor/zstd/CompressionPluginZstd.h | 2 +-
 src/compressor/zstd/ZstdCompressor.h        | 8 ++++----
 4 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/common/legacy_config_opts.h b/src/common/legacy_config_opts.h
index cd7b78f1018a0..d206c7e4e352f 100644
--- a/src/common/legacy_config_opts.h
+++ b/src/common/legacy_config_opts.h
@@ -82,6 +82,7 @@ SAFE_OPTION(plugin_dir, OPT_STR)
 
 OPTION(compressor_zlib_isal, OPT_BOOL)
 OPTION(compressor_zlib_level, OPT_INT) //regular zlib compression level, not applicable to isa-l optimized version
+OPTION(compressor_zstd_level, OPT_INT) //regular zstd compression level
 
 OPTION(qat_compressor_enabled, OPT_BOOL)
 
diff --git a/src/common/options.cc b/src/common/options.cc
index 2af36dd0e4ef3..46efcc6a2fbad 100644
--- a/src/common/options.cc
+++ b/src/common/options.cc
@@ -785,6 +785,10 @@ std::vector<Option> get_global_options() {
     .set_default(5)
     .set_description("Zlib compression level to use"),
 
+    Option("compressor_zstd_level", Option::TYPE_INT, Option::LEVEL_ADVANCED)
+    .set_default(5)
+    .set_description("Zstd compression level to use"),
+
     Option("qat_compressor_enabled", Option::TYPE_BOOL, Option::LEVEL_ADVANCED)
     .set_default(false)
     .set_description("Enable Intel QAT acceleration support for compression if available"),
diff --git a/src/compressor/zstd/CompressionPluginZstd.h b/src/compressor/zstd/CompressionPluginZstd.h
index c85951705a406..72ef9c45ce010 100644
--- a/src/compressor/zstd/CompressionPluginZstd.h
+++ b/src/compressor/zstd/CompressionPluginZstd.h
@@ -32,7 +32,7 @@ class CompressionPluginZstd : public CompressionPlugin {
                       std::ostream *ss) override
   {
     if (compressor == 0) {
-      ZstdCompressor *interface = new ZstdCompressor();
+      ZstdCompressor *interface = new ZstdCompressor(cct);
       compressor = CompressorRef(interface);
     }
     *cs = compressor;
diff --git a/src/compressor/zstd/ZstdCompressor.h b/src/compressor/zstd/ZstdCompressor.h
index e51ba3b7cbd32..27812f0a834d0 100644
--- a/src/compressor/zstd/ZstdCompressor.h
+++ b/src/compressor/zstd/ZstdCompressor.h
@@ -22,15 +22,13 @@
 #include "include/encoding.h"
 #include "compressor/Compressor.h"
 
-#define COMPRESSION_LEVEL 5
-
 class ZstdCompressor : public Compressor {
  public:
-  ZstdCompressor() : Compressor(COMP_ALG_ZSTD, "zstd") {}
+  ZstdCompressor(CephContext *cct) : Compressor(COMP_ALG_ZSTD, "zstd"), cct(cct) {}
 
   int compress(const bufferlist &src, bufferlist &dst) override {
     ZSTD_CStream *s = ZSTD_createCStream();
-    ZSTD_initCStream_srcSize(s, COMPRESSION_LEVEL, src.length());
+    ZSTD_initCStream_srcSize(s, cct->_conf->compressor_zstd_level, src.length());
     auto p = src.begin();
     size_t left = src.length();
 
@@ -101,6 +99,8 @@ class ZstdCompressor : public Compressor {
     dst.append(dstptr, 0, outbuf.pos);
     return 0;
   }
+ private:
+  CephContext *const cct;
 };
 
 #endif

From d27799aec4c9dd9add678e864a7e1c0b988bafa8 Mon Sep 17 00:00:00 2001
From: Bryan Stillwell <bstillwell@godaddy.com>
Date: Fri, 11 Sep 2020 16:55:32 -0600
Subject: [PATCH 2/2] compressor: Set the Zstd default compression level to 1

The default compression level of 5 for Zstandard is too high for the majority
of use cases since it requires too many CPU cycles.  This patch switches the
default to 1.

Signed-off-by: Bryan Stillwell <bstillwell@godaddy.com>
---
 src/common/options.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common/options.cc b/src/common/options.cc
index 46efcc6a2fbad..70ace312853ad 100644
--- a/src/common/options.cc
+++ b/src/common/options.cc
@@ -786,7 +786,7 @@ std::vector<Option> get_global_options() {
     .set_description("Zlib compression level to use"),
 
     Option("compressor_zstd_level", Option::TYPE_INT, Option::LEVEL_ADVANCED)
-    .set_default(5)
+    .set_default(1)
     .set_description("Zstd compression level to use"),
 
     Option("qat_compressor_enabled", Option::TYPE_BOOL, Option::LEVEL_ADVANCED)