commit 3d952b461dd305951a1a566eafd87874e1b2849a
parent 71fd30b75ad028dfce69563792547f06fdf9d3c2
Author: Nick Mathewson <nickm@torproject.org>
Date: Thu, 21 Jan 2021 13:37:21 -0500
Merge remote-tracking branch 'tor-gitlab/mr/269' into maint-0.4.5
Diffstat:
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/changes/bug24857 b/changes/bug24857
@@ -0,0 +1,6 @@
+ o Minor bugfixes (directory cache, performance, windows):
+ - Limit the number of items in the consensus diff cache to 64 on Windows.
+ We hope this will resolve an issue where Windows relay operators reported
+ Tor using 100% CPU while we investigate better solutions. Fixes bug 24857;
+ bugfix on tor-0.3.1.1-alpha.
+
diff --git a/src/feature/dircache/consdiffmgr.c b/src/feature/dircache/consdiffmgr.c
@@ -177,6 +177,16 @@ typedef struct cdm_diff_t {
/** Hashtable mapping flavor and source consensus digest to status. */
static HT_HEAD(cdm_diff_ht, cdm_diff_t) cdm_diff_ht = HT_INITIALIZER();
+#ifdef _WIN32
+ // XXX(ahf): For tor#24857, a contributor suggested that on Windows, the CPU
+ // begins to spike at 100% once the number of files handled by the consensus
+ // diff manager becomes larger than 64. To see if the issue goes away, we
+ // hardcode this value to 64 now while we investigate a better solution.
+# define CACHE_MAX_NUM 64
+#else
+# define CACHE_MAX_NUM 128
+#endif
+
/**
* Configuration for this module
*/
@@ -184,7 +194,7 @@ static consdiff_cfg_t consdiff_cfg = {
// XXXX I'd like to make this number bigger, but it interferes with the
// XXXX seccomp2 syscall filter, which tops out at BPF_MAXINS (4096)
// XXXX rules.
- /* .cache_max_num = */ 128
+ /* .cache_max_num = */ CACHE_MAX_NUM
};
static int consdiffmgr_ensure_space_for_files(int n);
