[XFS] Improve buffered read throughput by removing unnecessary timer calls
that showed in ´kernel profiles.
SGI-PV: 925163
SGI-Modid: xfs-linux:xfs-kern:23861a
Signed-off-by: Nathan Scott <nathans@sgi.com>
diff --git a/fs/xfs/linux-2.6/xfs_iops.c b/fs/xfs/linux-2.6/xfs_iops.c
index 77708a8..68c83ec 100644
--- a/fs/xfs/linux-2.6/xfs_iops.c
+++ b/fs/xfs/linux-2.6/xfs_iops.c
@@ -69,6 +69,137 @@
#include <linux/xattr.h>
#include <linux/namei.h>
+/*
+ * Change the requested timestamp in the given inode.
+ * We don't lock across timestamp updates, and we don't log them but
+ * we do record the fact that there is dirty information in core.
+ *
+ * NOTE -- callers MUST combine XFS_ICHGTIME_MOD or XFS_ICHGTIME_CHG
+ * with XFS_ICHGTIME_ACC to be sure that access time
+ * update will take. Calling first with XFS_ICHGTIME_ACC
+ * and then XFS_ICHGTIME_MOD may fail to modify the access
+ * timestamp if the filesystem is mounted noacctm.
+ */
+void
+xfs_ichgtime(
+ xfs_inode_t *ip,
+ int flags)
+{
+ struct inode *inode = LINVFS_GET_IP(XFS_ITOV(ip));
+ timespec_t tv;
+
+ /*
+ * We're not supposed to change timestamps in readonly-mounted
+ * filesystems. Throw it away if anyone asks us.
+ */
+ if (unlikely(IS_RDONLY(inode)))
+ return;
+
+ /*
+ * Don't update access timestamps on reads if mounted "noatime".
+ * Throw it away if anyone asks us.
+ */
+ if (unlikely(
+ (ip->i_mount->m_flags & XFS_MOUNT_NOATIME || IS_NOATIME(inode)) &&
+ (flags & (XFS_ICHGTIME_ACC|XFS_ICHGTIME_MOD|XFS_ICHGTIME_CHG)) ==
+ XFS_ICHGTIME_ACC))
+ return;
+
+ nanotime(&tv);
+ if (flags & XFS_ICHGTIME_MOD) {
+ inode->i_mtime = tv;
+ ip->i_d.di_mtime.t_sec = (__int32_t)tv.tv_sec;
+ ip->i_d.di_mtime.t_nsec = (__int32_t)tv.tv_nsec;
+ }
+ if (flags & XFS_ICHGTIME_ACC) {
+ inode->i_atime = tv;
+ ip->i_d.di_atime.t_sec = (__int32_t)tv.tv_sec;
+ ip->i_d.di_atime.t_nsec = (__int32_t)tv.tv_nsec;
+ }
+ if (flags & XFS_ICHGTIME_CHG) {
+ inode->i_ctime = tv;
+ ip->i_d.di_ctime.t_sec = (__int32_t)tv.tv_sec;
+ ip->i_d.di_ctime.t_nsec = (__int32_t)tv.tv_nsec;
+ }
+
+ /*
+ * We update the i_update_core field _after_ changing
+ * the timestamps in order to coordinate properly with
+ * xfs_iflush() so that we don't lose timestamp updates.
+ * This keeps us from having to hold the inode lock
+ * while doing this. We use the SYNCHRONIZE macro to
+ * ensure that the compiler does not reorder the update
+ * of i_update_core above the timestamp updates above.
+ */
+ SYNCHRONIZE();
+ ip->i_update_core = 1;
+ if (!(inode->i_state & I_LOCK))
+ mark_inode_dirty_sync(inode);
+}
+
+/*
+ * Variant on the above which avoids querying the system clock
+ * in situations where we know the Linux inode timestamps have
+ * just been updated (and so we can update our inode cheaply).
+ * We also skip the readonly and noatime checks here, they are
+ * also catered for already.
+ */
+void
+xfs_ichgtime_fast(
+ xfs_inode_t *ip,
+ struct inode *inode,
+ int flags)
+{
+ timespec_t *tvp;
+
+ /*
+ * We're not supposed to change timestamps in readonly-mounted
+ * filesystems. Throw it away if anyone asks us.
+ */
+ if (unlikely(IS_RDONLY(inode)))
+ return;
+
+ /*
+ * Don't update access timestamps on reads if mounted "noatime".
+ * Throw it away if anyone asks us.
+ */
+ if (unlikely(
+ (ip->i_mount->m_flags & XFS_MOUNT_NOATIME || IS_NOATIME(inode)) &&
+ ((flags & (XFS_ICHGTIME_ACC|XFS_ICHGTIME_MOD|XFS_ICHGTIME_CHG)) ==
+ XFS_ICHGTIME_ACC)))
+ return;
+
+ if (flags & XFS_ICHGTIME_MOD) {
+ tvp = &inode->i_mtime;
+ ip->i_d.di_mtime.t_sec = (__int32_t)tvp->tv_sec;
+ ip->i_d.di_mtime.t_nsec = (__int32_t)tvp->tv_nsec;
+ }
+ if (flags & XFS_ICHGTIME_ACC) {
+ tvp = &inode->i_atime;
+ ip->i_d.di_atime.t_sec = (__int32_t)tvp->tv_sec;
+ ip->i_d.di_atime.t_nsec = (__int32_t)tvp->tv_nsec;
+ }
+ if (flags & XFS_ICHGTIME_CHG) {
+ tvp = &inode->i_ctime;
+ ip->i_d.di_ctime.t_sec = (__int32_t)tvp->tv_sec;
+ ip->i_d.di_ctime.t_nsec = (__int32_t)tvp->tv_nsec;
+ }
+
+ /*
+ * We update the i_update_core field _after_ changing
+ * the timestamps in order to coordinate properly with
+ * xfs_iflush() so that we don't lose timestamp updates.
+ * This keeps us from having to hold the inode lock
+ * while doing this. We use the SYNCHRONIZE macro to
+ * ensure that the compiler does not reorder the update
+ * of i_update_core above the timestamp updates above.
+ */
+ SYNCHRONIZE();
+ ip->i_update_core = 1;
+ if (!(inode->i_state & I_LOCK))
+ mark_inode_dirty_sync(inode);
+}
+
/*
* Pull the link count and size up from the xfs inode to the linux inode