[PATCH 2/7] - choose single default logbuf count & size

Eric Sandeen
2007-07-20T04:12:08Z

Remove sizing of logbuf size & count based on physical memory;
this was never a very good gauge as it's looking at global
memory, but deciding on sizing per-filesystem; no account
is made of the total number of filesystems, for example.

For now just take the largest "default" case, as was set
for machines with >400MB - 8 x 32k buffers. This can
always be tuned higher or lower with mount options
if necessary. Removes one more user of xfs_physmem.

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

Index: linux/fs/xfs/xfs_log.c
===================================================================
--- linux.orig/fs/xfs/xfs_log.c
+++ linux/fs/xfs/xfs_log.c
@@ -1025,10 +1025,7 @@ xlog_bdstrat_cb(struct xfs_buf *bp)
/*
* Return size of each in-core log record buffer.
*
- * Low memory machines only get 2 16KB buffers. We don't want to waste
- * memory here. However, all other machines get at least 2 32KB buffers.
- * The number is hard coded because we don't care about the minimum
- * memory size, just 32MB systems.
+ * All machines get 8 x 32KB buffers by default, unless tuned otherwise.
*
* If the filesystem blocksize is too large, we may need to choose a
* larger size since the directory code currently logs entire blocks.
@@ -1041,17 +1038,10 @@ xlog_get_iclog_buffer_size(xfs_mount_t *
int size;
int xhdrs;

- if (mp->m_logbufs <= 0) {
- if (xfs_physmem <= btoc(128*1024*1024)) {
- log->l_iclog_bufs = XLOG_MIN_ICLOGS;
- } else if (xfs_physmem <= btoc(400*1024*1024)) {
- log->l_iclog_bufs = XLOG_MED_ICLOGS;
- } else { /* 256K with 32K bufs */
- log->l_iclog_bufs = XLOG_MAX_ICLOGS;
- }
- } else {
+ if (mp->m_logbufs <= 0)
+ log->l_iclog_bufs = XLOG_MAX_ICLOGS;
+ else
log->l_iclog_bufs = mp->m_logbufs;
- }

/*
* Buffer size passed in from mount system call.
@@ -1082,18 +1072,9 @@ xlog_get_iclog_buffer_size(xfs_mount_t *
goto done;
}

- /*
- * Special case machines that have less than 32MB of memory.
- * All machines with more memory use 32KB buffers.
- */
- if (xfs_physmem <= btoc(32*1024*1024)) {
- /* Don't change; min configuration */
- log->l_iclog_size = XLOG_RECORD_BSIZE; /* 16k */
- log->l_iclog_size_log = XLOG_RECORD_BSHIFT;
- } else {
- log->l_iclog_size = XLOG_BIG_RECORD_BSIZE; /* 32k */
- log->l_iclog_size_log = XLOG_BIG_RECORD_BSHIFT;
- }
+ /* All machines use 32KB buffers by default. */
+ log->l_iclog_size = XLOG_BIG_RECORD_BSIZE;
+ log->l_iclog_size_log = XLOG_BIG_RECORD_BSHIFT;

/* the default log size is 16k or 32k which is one header sector */
log->l_iclog_hsize = BBSIZE;
Index: linux/fs/xfs/xfs_log_priv.h
===================================================================
--- linux.orig/fs/xfs/xfs_log_priv.h
+++ linux/fs/xfs/xfs_log_priv.h
@@ -30,7 +30,6 @@ struct xfs_mount;
*/

#define XLOG_MIN_ICLOGS 2
-#define XLOG_MED_ICLOGS 4
#define XLOG_MAX_ICLOGS 8
#define XLOG_HEADER_MAGIC_NUM 0xFEEDbabe /* Invalid cycle number */
#define XLOG_VERSION_1 1