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

[Eric Sandeen <sandeen@xxxxxxxxxxx>]

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@xxxxxxxxxxx>

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