Changes between Version 14 and Version 15 of RRDtool13

Timestamp:

Jun 14, 2007, 10:55:03 PM (15 years ago)

Author:

oetiker

Comment:

Added Info about IO performance.

RRDtool13

@@ -1 +1 @@
 = Features for RRDtool 1.3 =
+
+== Updates ==
+
+|| 2007-06-14 || Performance impact of MMAP IO and madvise quantified. ||
+||            || Added TEXTALIGN command                               ||
+
 
 == Completed ==
@@ -6 +12 @@
 
 The whole IO subsystem has been redone by Bernhard Fisher. It can now uses
-MMAPed IO for all rrd file access.
+MMAPed IO for all RRD file access and uses madvise extensively to help the kernel with cache handling.
 
-(Performance testing not done yet, but the load on the Kernel IO should be much lighter)
+The net effect is that in-memory updates are about twice as fast as before.
+My coreduo thnkpad was able todo 12k updates per second (in memory) with the
+1.2 code base while it is able to do 22k updates per second (in memory).
 
-=== Cairo/Pango ===
+Obviously RRD data has to go to disk eventually, there has not been all that much change, 
+since the OS still has to write the blocks. My 5400 RPM Thinkpad HD continues to get about250 Updates
+to disk per second.
+
+The interesting thing here is that we are telling the kernel that we will not read the whole RRDfile
+but just some blocks of it (random access). This helps optimize cache access and reduces disk IO.
+The main advantage of this is that the cache usage gets optimized. The number of RRDfiles
+that can be kept in cache at any one time is 3 to 5 times as large in 1.3 as in 1.2. 
+
+=== Graphing with Cairo/Pango ===
 
 No more libart, no more strange error messages about stability.
 The switch to Cairo makes for a number of neat new features:
 
- * --graph-render-mode=mono brings back the rrdtool 1.0.x look and feel[[BR]][[Image(minmax.mono.png)]][[BR]]. The antialiasing can be configured for
+ * --graph-render-mode=mono brings back the rrdtool 1.0.x look and feel[[BR]][[Image(minmax.mono.png)]][[BR]]. The anti aliasing can be configured for
    graph and fonts separately.
  * full grid-fitting of all drawing operations makes for crisper looking graph output
@@ -31 +48 @@
    font properties inside any rrdtool graph text field.
 
+=== Other Enhancements ===
+
+ TEXTALIGN::
+ The TEXTALIGN command lets you specify how the legend of the graph should be aligned by
+ default. 
+{{{
+ TEXTALIGN:left 
+}}}
 == Planned ==
 
@@ -36 +61 @@
  1. Architecture independent data format with xdr (tobi with help from Matt Massie)
  1. command line parsing with popt (or some other thread-safe thing) (tobi)
- 1. ALIGN:left|right|both function to alter the way rrdtool acts on encountering a full line. 
-    At the moment it justifies the line which may not look good in all cases
  
 == Maybe ==