From dd186998dd408c54ffe30df1cc35422e645e0ca2 Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Tue, 26 Nov 2013 18:58:44 +0100

Subject: [PATCH] journald: keep statistics on how of we hit/miss the mmap

 cache

(cherry picked from commit bf807d4dbf27c783db8dfd7f4eca321ae4be5b00)

---

 src/journal/mmap-cache.c | 25 +++++++++++++++++++++++--

 src/journal/mmap-cache.h |  3 +++

 src/journal/sd-journal.c |  4 +++-

 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/src/journal/mmap-cache.c b/src/journal/mmap-cache.c

index 03b57be..42a8a7d 100644

--- a/src/journal/mmap-cache.c

+++ b/src/journal/mmap-cache.c

@@ -72,6 +72,9 @@ struct MMapCache {

         int n_ref;

         unsigned n_windows;

+        unsigned n_hit, n_missed;

+

+

         Hashmap *fds;

         Hashmap *contexts;

@@ -542,13 +545,19 @@ int mmap_cache_get(

         /* Check whether the current context is the right one already */

         r = try_context(m, fd, prot, context, keep_always, offset, size, ret);

-        if (r != 0)

+        if (r != 0) {

+                m->n_hit ++;

                 return r;

+        }

         /* Search for a matching mmap */

         r = find_mmap(m, fd, prot, context, keep_always, offset, size, ret);

-        if (r != 0)

+        if (r != 0) {

+                m->n_hit ++;

                 return r;

+        }

+

+        m->n_missed++;

         /* Create a new mmap */

         return add_mmap(m, fd, prot, context, keep_always, offset, size, st, ret);

@@ -578,3 +587,15 @@ void mmap_cache_close_context(MMapCache *m, unsigned context) {

         context_free(c);

 }

+

+unsigned mmap_cache_get_hit(MMapCache *m) {

+        assert(m);

+

+        return m->n_hit;

+}

+

+unsigned mmap_cache_get_missed(MMapCache *m) {

+        assert(m);

+

+        return m->n_missed;

+}

diff --git a/src/journal/mmap-cache.h b/src/journal/mmap-cache.h

index 0c42fb8..912336d 100644

--- a/src/journal/mmap-cache.h

+++ b/src/journal/mmap-cache.h

@@ -34,3 +34,6 @@ MMapCache* mmap_cache_unref(MMapCache *m);

 int mmap_cache_get(MMapCache *m, int fd, int prot, unsigned context, bool keep_always, uint64_t offset, size_t size, struct stat *st, void **ret);

 void mmap_cache_close_fd(MMapCache *m, int fd);

 void mmap_cache_close_context(MMapCache *m, unsigned context);

+

+unsigned mmap_cache_get_hit(MMapCache *m);

+unsigned mmap_cache_get_missed(MMapCache *m);

diff --git a/src/journal/sd-journal.c b/src/journal/sd-journal.c

index 9676f0f..52abbe9 100644

--- a/src/journal/sd-journal.c

+++ b/src/journal/sd-journal.c

@@ -1831,8 +1831,10 @@ _public_ void sd_journal_close(sd_journal *j) {

         if (j->inotify_fd >= 0)

                 close_nointr_nofail(j->inotify_fd);

-        if (j->mmap)

+        if (j->mmap) {

+                log_debug("mmap cache statistics: %u hit, %u miss", mmap_cache_get_hit(j->mmap), mmap_cache_get_missed(j->mmap));

                 mmap_cache_unref(j->mmap);

+        }

         free(j->path);

         free(j->unique_field);