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[PATCH 5/5] xfs: increase inode cluster size for v5 filesystems

To: xfs@xxxxxxxxxxx
Subject: [PATCH 5/5] xfs: increase inode cluster size for v5 filesystems
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Fri, 1 Nov 2013 15:27:20 +1100
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1383280040-21979-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1383280040-21979-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

v5 filesystems use 512 byte inodes as a minimum, so read inodes in
clusters that are effectively half the size of a v4 filesystem with
256 byte inodes. For v5 fielsystems, scale the inode cluster size
with the size of the inode so that we keep a constant 32 inodes per
cluster ratio for all inode IO.

This only works if mkfs.xfs sets the inode alignment appropriately
for larger inode clusters, so this functionality is made conditional
on mkfs doing the right thing. xfs_repair needs to know about
the inode alignment changes, too.

Wall time:
        create  bulkstat        find+stat       ls -R   unlink
v4      237s    161s            173s            201s    299s
v5      235s    163s            205s             31s    356s
patched 234s    160s            182s             29s    317s

System time:
        create  bulkstat        find+stat       ls -R   unlink
v4      2601s   2490s           1653s           1656s   2960s
v5      2637s   2497s           1681s             20s   3216s
patched 2613s   2451s           1658s             20s   3007s

So, wall time same or down across the board, system time same or
down across the board, and cache hit rates all improve except for
the ls -R case which is a pure cold cache directory read workload
on v5 filesystems...

So, this patch removes most of the performance and CPU usage
differential between v4 and v5 filesystems on traversal related
workloads.

Note: while this patch is currently for v5 filesystems only, there
is no reason it can't be ported back to v4 filesystems.  This hasn't
been done here because bringing the code back to v4 requires
forwards and backwards kernel compatibility testing.  i.e. to
deterine if older kernels(*) do the right thing with larger inode
alignments but still only using 8k inode cluster sizes. None of this
testing and validation on v4 filesystems has been done, so for the
moment larger inode clusters is limited to v5 superblocks.

(*) a current default config v4 filesystem should mount just fine on
2.6.23 (when lazy-count support was introduced), and so if we change
the alignment emitted by mkfs without a feature bit then we have to
make sure it works properly on all kernels since 2.6.23. And if we
allow it to be changed when the lazy-count bit is not set, then it's
all kernels since v2 logs were introduced that need to be tested for
compatibility...

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
 fs/xfs/xfs_mount.c      | 15 +++++++++++++++
 fs/xfs/xfs_mount.h      |  2 +-
 fs/xfs/xfs_trans_resv.c |  3 +--
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index da88f16..02df7b4 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -41,6 +41,7 @@
 #include "xfs_fsops.h"
 #include "xfs_trace.h"
 #include "xfs_icache.h"
+#include "xfs_dinode.h"
 
 
 #ifdef HAVE_PERCPU_SB
@@ -718,8 +719,22 @@ xfs_mountfs(
         * Set the inode cluster size.
         * This may still be overridden by the file system
         * block size if it is larger than the chosen cluster size.
+        *
+        * For v5 filesystems, scale the cluster size with the inode size to
+        * keep a constant ratio of inode per cluster buffer, but only if mkfs
+        * has set the inode alignment value appropriately for larger cluster
+        * sizes.
         */
        mp->m_inode_cluster_size = XFS_INODE_BIG_CLUSTER_SIZE;
+       if (xfs_sb_version_hascrc(&mp->m_sb)) {
+               int     new_size = mp->m_inode_cluster_size;
+
+               new_size *= mp->m_sb.sb_inodesize / XFS_DINODE_MIN_SIZE;
+               if (mp->m_sb.sb_inoalignmt >= XFS_B_TO_FSBT(mp, new_size))
+                       mp->m_inode_cluster_size = new_size;
+               xfs_info(mp, "Using inode cluster size of %d bytes",
+                        mp->m_inode_cluster_size);
+       }
 
        /*
         * Set inode alignment fields
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 1d8101a..a466c5e 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -112,7 +112,7 @@ typedef struct xfs_mount {
        __uint8_t               m_blkbb_log;    /* blocklog - BBSHIFT */
        __uint8_t               m_agno_log;     /* log #ag's */
        __uint8_t               m_agino_log;    /* #bits for agino in inum */
-       __uint16_t              m_inode_cluster_size;/* min inode buf size */
+       uint                    m_inode_cluster_size;/* min inode buf size */
        uint                    m_blockmask;    /* sb_blocksize-1 */
        uint                    m_blockwsize;   /* sb_blocksize in words */
        uint                    m_blockwmask;   /* blockwsize-1 */
diff --git a/fs/xfs/xfs_trans_resv.c b/fs/xfs/xfs_trans_resv.c
index d53d9f0..2fd59c0 100644
--- a/fs/xfs/xfs_trans_resv.c
+++ b/fs/xfs/xfs_trans_resv.c
@@ -385,8 +385,7 @@ xfs_calc_ifree_reservation(
                xfs_calc_inode_res(mp, 1) +
                xfs_calc_buf_res(2, mp->m_sb.sb_sectsize) +
                xfs_calc_buf_res(1, XFS_FSB_TO_B(mp, 1)) +
-               MAX((__uint16_t)XFS_FSB_TO_B(mp, 1),
-                   XFS_INODE_CLUSTER_SIZE(mp)) +
+               max_t(uint, XFS_FSB_TO_B(mp, 1), XFS_INODE_CLUSTER_SIZE(mp)) +
                xfs_calc_buf_res(1, 0) +
                xfs_calc_buf_res(2 + XFS_IALLOC_BLOCKS(mp) +
                                 mp->m_in_maxlevels, 0) +
-- 
1.8.4.rc3

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