From 7943f42275025e1b6642b580b19b24dfab8dee61 Mon Sep 17 00:00:00 2001 From: Michal Schmidt Date: Wed, 17 Dec 2014 15:07:25 +0100 Subject: 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 --- src/journal/sd-journal.c | 6 ++++++ 1 file changed, 6 insertions(+) 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); -- cgit v1.2.3-54-g00ecf