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authorMichal Schmidt <mschmidt@redhat.com>2014-12-17 15:07:25 +0100
committerMichal Schmidt <mschmidt@redhat.com>2014-12-18 14:35:30 +0100
commit7943f42275025e1b6642b580b19b24dfab8dee61 (patch)
treede4b31ad2a1996ba062c164c8f5197e1f2975e10
parent6e693b42dcb0b332364b0414107826826925c49f (diff)
journal: optimize iteration by returning previously found candidate entry
In next_beyond_location() when the JournalFile's location type is LOCATION_SEEK, it means there's nothing to do, because we already have the location of the candidate entry. Do an early return. Note that now next_beyond_location() does not anymore guarantee on return that the entry is mapped, but previous patches made sure the caller does not care. This optimization is at least as good as "journal: optimize iteration: skip files that cannot improve current candidate entry" was. Timing results on my workstation, using: $ time ./journalctl -q --since=2014-06-01 --until=2014-07-01 > /dev/null Before "Revert "journal: optimize iteration: skip files that cannot improve current candidate entry": real 0m5.349s user 0m5.166s sys 0m0.181s Now: real 0m3.901s user 0m3.724s sys 0m0.176s
-rw-r--r--src/journal/sd-journal.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/src/journal/sd-journal.c b/src/journal/sd-journal.c
index 0aaf2257d4..0fefe2bc6e 100644
--- a/src/journal/sd-journal.c
+++ b/src/journal/sd-journal.c
@@ -742,6 +742,12 @@ static int next_beyond_location(sd_journal *j, JournalFile *f, direction_t direc
f->last_n_entries = n_entries;
if (f->last_direction == direction && f->current_offset > 0) {
+ /* LOCATION_SEEK here means we did the work in a previous
+ * iteration and the current location already points to a
+ * candidate entry. */
+ if (f->location_type == LOCATION_SEEK)
+ return 1;
+
cp = f->current_offset;
r = journal_file_move_to_object(f, OBJECT_ENTRY, cp, &c);