config: add new index.threads config setting
Add support for a new index.threads config setting which will be used to control the threading code in do_read_index(). A value of 0 will tell the index code to automatically determine the correct number of threads to use. A value of 1 will make the code single threaded. A value greater than 1 will set the maximum number of threads to use. For testing purposes, this setting can be overwritten by setting the GIT_TEST_INDEX_THREADS=<n> environment variable to a value greater than 0. Signed-off-by: Ben Peart <benpeart@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Ben Peart committed
Oct 10, 2018 at 11:59 UTC
c780b9cfe8d79331ed9797e328b1bf80666c4ac2
5 files changed
+36
Documentation/config.txt
+7
@@ -2413,6 +2413,13 @@ imap::
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The configuration variables in the 'imap' section are described
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in linkgit:git-imap-send[1].
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+index.threads::
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+ Specifies the number of threads to spawn when loading the index.
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+ This is meant to reduce index load time on multiprocessor machines.
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+ Specifying 0 or 'true' will cause Git to auto-detect the number of
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+ CPU's and set the number of threads accordingly. Specifying 1 or
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+ 'false' will disable multithreading. Defaults to 'true'.
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+
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index.version::
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Specify the version with which new index files should be
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initialized. This does not affect existing repositories.
config.c
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@@ -2289,6 +2289,24 @@ int git_config_get_fsmonitor(void)
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return 0;
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}
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+int git_config_get_index_threads(void)
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+{
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+ int is_bool, val = 0;
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+
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+ val = git_env_ulong("GIT_TEST_INDEX_THREADS", 0);
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+ if (val)
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+ return val;
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+
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+ if (!git_config_get_bool_or_int("index.threads", &is_bool, &val)) {
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+ if (is_bool)
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+ return val ? 0 : 1;
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+ else
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+ return val;
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+ }
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+
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+ return 0; /* auto */
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+}
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+
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NORETURN
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void git_die_config_linenr(const char *key, const char *filename, int linenr)
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{
config.h
+1
@@ -250,6 +250,7 @@ extern int git_config_get_untracked_cache(void);
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extern int git_config_get_split_index(void);
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extern int git_config_get_max_percent_split_change(void);
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extern int git_config_get_fsmonitor(void);
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+extern int git_config_get_index_threads(void);
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/* This dies if the configured or default date is in the future */
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extern int git_config_get_expiry(const char *key, const char **output);
t/README
+5
@@ -327,6 +327,11 @@ GIT_TEST_COMMIT_GRAPH=<boolean>, when true, forces the commit-graph to
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be written after every 'git commit' command, and overrides the
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'core.commitGraph' setting to true.
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+GIT_TEST_INDEX_THREADS=<n> enables exercising the multi-threaded loading
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+of the index for the whole test suite by bypassing the default number of
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+cache entries and thread minimums. Setting this to 1 will make the
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+index loading single threaded.
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+
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Naming Tests
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------------
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t/t1700-split-index.sh
+5
@@ -6,7 +6,12 @@ test_description='split index mode tests'
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# We need total control of index splitting here
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sane_unset GIT_TEST_SPLIT_INDEX
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+
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+# Testing a hard coded SHA against an index with an extension
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+# that can vary from run to run is problematic so we disable
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+# those extensions.
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sane_unset GIT_FSMONITOR_TEST
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+sane_unset GIT_TEST_INDEX_THREADS
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test_expect_success 'enable split index' '
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git config splitIndex.maxPercentChange 100 &&