This updates the vm/bdflush description to accurately reflect the
values in /proc. The descriptions won't win any prizes, but at least
the variable table is correct.
--- linux-2.4.19-rc1/Documentation/filesystems/proc.txt Sun Jul 7 20:40:04 2002
+++ linux-2.4.19-rc1-new/Documentation/filesystems/proc.txt Sun Jul 7 20:46:36 2002
@@ -961,17 +961,17 @@
Table 2-2: Parameters in /proc/sys/vm/bdflush
..............................................................................
- Value Meaning
- nfract Percentage of buffer cache dirty to activate bdflush
- ndirty Maximum number of dirty blocks to write out per wake-cycle
- nrefill Number of clean buffers to try to obtain each time we call refill
- nref_dirt buffer threshold for activating bdflush when trying to refill
- buffers.
- dummy Unused
- age_buffer Time for normal buffer to age before we flush it
- age_super Time for superblock to age before we flush it
- dummy Unused
- dummy Unused
+ Value Meaning
+ ----- -------
+ nfract Percentage of buffer cache dirty to activate bdflush
+ ndirty Maximum number of dirty blocks to write out per wake-cycle
+ dummy Unused
+ dummy Unused
+ interval Time between kupdate flushes
+ age_buffer Time for normal buffer to age before we flush it
+ nfract_sync Percentage of buffer cache dirty to activate bdflush synchronously
+ nfract_stop Percentage of buffer cache dirty to stop bdflush
+ dummy Unused
..............................................................................
nfract
@@ -991,29 +991,25 @@
disk at one time. A high value will mean delayed, bursty I/O, while a small
value can lead to memory shortage when bdflush isn't woken up often enough.
-nrefill
--------
+interval
+--------
-This is the number of buffers that bdflush will add to the list of free
-buffers when refill_freelist() is called. It is necessary to allocate free
-buffers beforehand, since the buffers are often different sizes than the
-memory pages and some bookkeeping needs to be done beforehand. The higher the
-number, the more memory will be wasted and the less often refill_freelist()
-will need to run.
+Interval specifies the time in jiffies (clockticks) between kupdated flushes.
+The default number of jiffies per second is 100.
-nref_dirt
----------
+age_buffer
+----------
-When refill_freelist() comes across more than nref_dirt dirty buffers, it will
-wake up bdflush.
+Age_buffer specifies the maximum time Linux waits before writing out a dirty
+buffer to disk. The value is expressed in jiffies (clockticks) and the default
+number of jiffies per second is 100. Age_buffer is the maximum age for data
+blocks.
-age_buffer and age_super
-------------------------
+nfract_sync and nfract_stop_bdflush
+-----------------------------------
-Finally, the age_buffer and age_super parameters govern the maximum time Linux
-waits before writing out a dirty buffer to disk. The value is expressed in
-jiffies (clockticks), the number of jiffies per second is 100. Age_buffer is
-the maximum age for data blocks, while age_super is for filesystems meta data.
+These follow the same general rules as nfract above, but values specify limits
+determining when synchronous flushing starts and flushing ends, respectively.
buffermem
---------
-
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