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This is simply 50 messages from the early history of the notmuch mailing list, (fetched from the public archives).
121 lines
3.7 KiB
Text
121 lines
3.7 KiB
Text
From: "Stewart Smith" <stewart@flamingspork.com>
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To: notmuch@notmuchmail.org
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Date: Wed, 18 Nov 2009 12:56:40 +1100
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Subject: [notmuch] [PATCH 2/2] Read mail directory in inode number order
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Message-ID: <1258509400-32511-1-git-send-email-stewart@flamingspork.com>
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This gives a rather decent reduction in number of seeks required when
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reading a Maildir that isn't in pagecache.
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Most filesystems give some locality on disk based on inode numbers.
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In ext[234] this is the inode tables, in XFS groups of sequential inode
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numbers are together on disk and the most significant bits indicate
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allocation group (i.e inode 1,000,000 is always after inode 1,000).
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With this patch, we read in the whole directory, sort by inode number
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before stat()ing the contents.
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Ideally, directory is sequential and then we make one scan through the
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file system stat()ing.
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Since the universe is not ideal, we'll probably seek during reading the
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directory and a fair bit while reading the inodes themselves.
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However... with readahead, and stat()ing in inode order, we should be
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in the best place possible to hit the cache.
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In a (not very good) benchmark of "how long does it take to find the first
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15,000 messages in my Maildir after 'echo 3 > /proc/sys/vm/drop_caches'",
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this patch consistently cut at least 8 seconds off the scan time.
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Without patch: 50 seconds
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With patch: 38-42 seconds.
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(I did this in a previous maildir reading project and saw large improvements too)
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---
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notmuch-new.c | 32 +++++++++++++++-----------------
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1 files changed, 15 insertions(+), 17 deletions(-)
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diff --git a/notmuch-new.c b/notmuch-new.c
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index 83a05ba..11fad8c 100644
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--- a/notmuch-new.c
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+++ b/notmuch-new.c
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@@ -73,6 +73,11 @@ add_files_print_progress (add_files_state_t *state)
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fflush (stdout);
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}
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+static int ino_cmp(const struct dirent **a, const struct dirent **b)
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+{
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+ return ((*a)->d_ino < (*b)->d_ino)? -1: 1;
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+}
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+
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/* Examine 'path' recursively as follows:
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*
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* o Ask the filesystem for the mtime of 'path' (path_mtime)
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@@ -100,13 +105,12 @@ add_files_recursive (notmuch_database_t *notmuch,
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add_files_state_t *state)
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{
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DIR *dir = NULL;
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- struct dirent *e, *entry = NULL;
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- int entry_length;
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- int err;
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+ struct dirent *entry = NULL;
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char *next = NULL;
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time_t path_mtime, path_dbtime;
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notmuch_status_t status, ret = NOTMUCH_STATUS_SUCCESS;
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notmuch_message_t *message = NULL;
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+ struct dirent **namelist = NULL;
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/* If we're told to, we bail out on encountering a read-only
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* directory, (with this being a clear clue from the user to
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@@ -122,31 +126,23 @@ add_files_recursive (notmuch_database_t *notmuch,
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path_mtime = st->st_mtime;
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path_dbtime = notmuch_database_get_timestamp (notmuch, path);
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+ int n_entries= scandir(path, &namelist, 0, ino_cmp);
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- dir = opendir (path);
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- if (dir == NULL) {
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+ if (n_entries == -1) {
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fprintf (stderr, "Error opening directory %s: %s\n",
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path, strerror (errno));
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ret = NOTMUCH_STATUS_FILE_ERROR;
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goto DONE;
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}
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- entry_length = offsetof (struct dirent, d_name) +
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- pathconf (path, _PC_NAME_MAX) + 1;
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- entry = malloc (entry_length);
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+ int i=0;
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while (!interrupted) {
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- err = readdir_r (dir, entry, &e);
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- if (err) {
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- fprintf (stderr, "Error reading directory: %s\n",
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- strerror (errno));
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- ret = NOTMUCH_STATUS_FILE_ERROR;
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- goto DONE;
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- }
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-
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- if (e == NULL)
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+ if (i == n_entries)
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break;
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+ entry= namelist[i++];
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+
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/* If this directory hasn't been modified since the last
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* add_files, then we only need to look further for
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* sub-directories. */
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@@ -243,6 +239,8 @@ add_files_recursive (notmuch_database_t *notmuch,
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free (entry);
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if (dir)
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closedir (dir);
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+ if (namelist)
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+ free (namelist);
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return ret;
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}
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--
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1.6.3.3
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