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From: Dave Chinner <david@fromorbit.com>
To: xfs@oss.sgi.com
Subject: [PATCH 01/10] repair: translation lookups limit scalability
Date: Thu, 27 Feb 2014 20:51:06 +1100	[thread overview]
Message-ID: <1393494675-30194-2-git-send-email-david@fromorbit.com> (raw)
In-Reply-To: <1393494675-30194-1-git-send-email-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

A bit of perf magic showed that scalability was limits to 3-4
concurrent threads due to contention on a lock inside in something
called __dcigettext(). That some library somewhere that repair is
linked against, and it turns out to be inside the translation
infrastructure to support the _() string mechanism:

# Samples: 34K of event 'cs'
# Event count (approx.): 495567
#
# Overhead        Command      Shared Object          Symbol
# ........  .............  .................  ..............
#
    60.30%     xfs_repair  [kernel.kallsyms]  [k] __schedule
               |
               --- 0x63fffff9c
                   process_bmbt_reclist_int
                  |
                  |--39.95%-- __dcigettext
                  |          __lll_lock_wait
                  |          system_call_fastpath
                  |          SyS_futex
                  |          do_futex
                  |          futex_wait
                  |          futex_wait_queue_me
                  |          schedule
                  |          __schedule
                  |
                  |--8.91%-- __lll_lock_wait
                  |          system_call_fastpath
                  |          SyS_futex
                  |          do_futex
                  |          futex_wait
                  |          futex_wait_queue_me
                  |          schedule
                  |          __schedule
                   --51.13%-- [...]

Fix this by initialising global variables that hold the translated
strings at startup, hence avoiding the need to do repeated runtime
translation of the same strings.

Runtime of an unpatched xfs_repair is roughly:

        XFS_REPAIR Summary    Fri Dec  6 11:15:50 2013

Phase           Start           End             Duration
Phase 1:        12/06 10:56:21  12/06 10:56:21
Phase 2:        12/06 10:56:21  12/06 10:56:23  2 seconds
Phase 3:        12/06 10:56:23  12/06 11:01:31  5 minutes, 8 seconds
Phase 4:        12/06 11:01:31  12/06 11:07:08  5 minutes, 37 seconds
Phase 5:        12/06 11:07:08  12/06 11:07:09  1 second
Phase 6:        12/06 11:07:09  12/06 11:15:49  8 minutes, 40 seconds
Phase 7:        12/06 11:15:49  12/06 11:15:50  1 second

Total run time: 19 minutes, 29 seconds

Patched version:

Phase           Start           End             Duration
Phase 1:        12/06 10:36:29  12/06 10:36:29
Phase 2:        12/06 10:36:29  12/06 10:36:31  2 seconds
Phase 3:        12/06 10:36:31  12/06 10:40:08  3 minutes, 37 seconds
Phase 4:        12/06 10:40:08  12/06 10:43:42  3 minutes, 34 seconds
Phase 5:        12/06 10:43:42  12/06 10:43:42
Phase 6:        12/06 10:43:42  12/06 10:50:28  6 minutes, 46 seconds
Phase 7:        12/06 10:50:28  12/06 10:50:29  1 second

Total run time: 14 minutes

Big win!

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
 repair/dinode.c     | 49 +++++++++++++++++++++++++++++++++++--------------
 repair/dinode.h     |  3 +++
 repair/scan.c       |  7 +------
 repair/xfs_repair.c |  2 ++
 4 files changed, 41 insertions(+), 20 deletions(-)

diff --git a/repair/dinode.c b/repair/dinode.c
index 3115bd0..4953a56 100644
--- a/repair/dinode.c
+++ b/repair/dinode.c
@@ -32,6 +32,37 @@
 #include "threads.h"
 
 /*
+ * gettext lookups for translations of strings use mutexes internally to
+ * the library. Hence when we come through here doing parallel scans in
+ * multiple AGs, then all do concurrent text conversions and serialise
+ * on the translation string lookups. Let's avoid doing repeated lookups
+ * by making them static variables and only assigning the translation
+ * once.
+ */
+static char	*forkname_data;
+static char	*forkname_attr;
+static char	*ftype_real_time;
+static char	*ftype_regular;
+
+void
+dinode_bmbt_translation_init(void)
+{
+	forkname_data = _("data");
+	forkname_attr = _("attr");
+	ftype_real_time = _("real-time");
+	ftype_regular = _("regular");
+}
+
+char *
+get_forkname(int whichfork)
+{
+
+	if (whichfork == XFS_DATA_FORK)
+		return forkname_data;
+	return forkname_attr;
+}
+
+/*
  * inode clearing routines
  */
 
@@ -542,7 +573,7 @@ process_bmbt_reclist_int(
 	xfs_dfiloff_t		op = 0;		/* prev offset */
 	xfs_dfsbno_t		b;
 	char			*ftype;
-	char			*forkname;
+	char			*forkname = get_forkname(whichfork);
 	int			i;
 	int			state;
 	xfs_agnumber_t		agno;
@@ -552,15 +583,10 @@ process_bmbt_reclist_int(
 	xfs_agnumber_t		locked_agno = -1;
 	int			error = 1;
 
-	if (whichfork == XFS_DATA_FORK)
-		forkname = _("data");
-	else
-		forkname = _("attr");
-
 	if (type == XR_INO_RTDATA)
-		ftype = _("real-time");
+		ftype = ftype_real_time;
 	else
-		ftype = _("regular");
+		ftype = ftype_regular;
 
 	for (i = 0; i < *numrecs; i++) {
 		libxfs_bmbt_disk_get_all(rp + i, &irec);
@@ -1110,7 +1136,7 @@ process_btinode(
 	xfs_ino_t		lino;
 	xfs_bmbt_ptr_t		*pp;
 	xfs_bmbt_key_t		*pkey;
-	char			*forkname;
+	char			*forkname = get_forkname(whichfork);
 	int			i;
 	int			level;
 	int			numrecs;
@@ -1122,11 +1148,6 @@ process_btinode(
 	*tot = 0;
 	*nex = 0;
 
-	if (whichfork == XFS_DATA_FORK)
-		forkname = _("data");
-	else
-		forkname = _("attr");
-
 	magic = xfs_sb_version_hascrc(&mp->m_sb) ? XFS_BMAP_CRC_MAGIC
 						 : XFS_BMAP_MAGIC;
 
diff --git a/repair/dinode.h b/repair/dinode.h
index d9197c1..7521521 100644
--- a/repair/dinode.h
+++ b/repair/dinode.h
@@ -127,4 +127,7 @@ get_bmapi(xfs_mount_t		*mp,
 		xfs_dfiloff_t	bno,
 		int             whichfork );
 
+void dinode_bmbt_translation_init(void);
+char * get_forkname(int whichfork);
+
 #endif /* _XR_DINODE_H */
diff --git a/repair/scan.c b/repair/scan.c
index 73b4581..b12f48b 100644
--- a/repair/scan.c
+++ b/repair/scan.c
@@ -171,17 +171,12 @@ scan_bmapbt(
 	xfs_bmbt_rec_t		*rp;
 	xfs_dfiloff_t		first_key;
 	xfs_dfiloff_t		last_key;
-	char			*forkname;
+	char			*forkname = get_forkname(whichfork);
 	int			numrecs;
 	xfs_agnumber_t		agno;
 	xfs_agblock_t		agbno;
 	int			state;
 
-	if (whichfork == XFS_DATA_FORK)
-		forkname = _("data");
-	else
-		forkname = _("attr");
-
 	/*
 	 * unlike the ag freeblock btrees, if anything looks wrong
 	 * in an inode bmap tree, just bail.  it's possible that
diff --git a/repair/xfs_repair.c b/repair/xfs_repair.c
index 9e0502a..bac334f 100644
--- a/repair/xfs_repair.c
+++ b/repair/xfs_repair.c
@@ -29,6 +29,7 @@
 #include "prefetch.h"
 #include "threads.h"
 #include "progress.h"
+#include "dinode.h"
 
 #define	rounddown(x, y)	(((x)/(y))*(y))
 
@@ -533,6 +534,7 @@ main(int argc, char **argv)
 	setlocale(LC_ALL, "");
 	bindtextdomain(PACKAGE, LOCALEDIR);
 	textdomain(PACKAGE);
+	dinode_bmbt_translation_init();
 
 	temp_mp = &xfs_m;
 	setbuf(stdout, NULL);
-- 
1.8.4.rc3

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  reply	other threads:[~2014-02-27  9:51 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-27  9:51 [PATCH 00/10, v3] xfsprogs: reapir scalability and fixes Dave Chinner
2014-02-27  9:51 ` Dave Chinner [this message]
2014-02-27  9:51 ` [PATCH 02/10] repair: per AG locks contend for cachelines Dave Chinner
2014-02-27  9:51 ` [PATCH 03/10] libxfs: buffer cache hashing is suboptimal Dave Chinner
2014-02-27  9:51 ` [PATCH 04/10] repair: limit auto-striding concurrency apprpriately Dave Chinner
2014-02-27  9:51 ` [PATCH 05/10] repair: use a listhead for the dotdot list Dave Chinner
2014-02-27  9:51 ` [PATCH 06/10] repair: fix prefetch queue limiting Dave Chinner
2014-02-27  9:51 ` [PATCH 07/10] repair: BMBT prefetch needs to be CRC aware Dave Chinner
2014-02-27  9:51 ` [PATCH 08/10] repair: factor out threading setup code Dave Chinner
2014-02-27 14:05   ` Brian Foster
2014-02-27  9:51 ` [PATCH 09/10] repair: prefetch runs too far ahead Dave Chinner
2014-02-27 14:08   ` Brian Foster
2014-02-27 20:01     ` Dave Chinner
2014-02-27 20:24       ` Dave Chinner
2014-02-27 20:45         ` Brian Foster
2014-02-27  9:51 ` [PATCH 10/10] libxfs: remove a couple of locks Dave Chinner
  -- strict thread matches above, loose matches on Subject: below --
2014-02-24  6:29 [PATCH 00/10, v2] repair: scalability and prefetch fixes Dave Chinner
2014-02-24  6:29 ` [PATCH 01/10] repair: translation lookups limit scalability Dave Chinner
2014-02-24 20:42   ` Brian Foster
2014-02-25 20:01   ` Christoph Hellwig

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