observed significant performance improvement using "delaylog" in a real-world application
niemayer at isg.de
Wed Aug 11 04:45:41 CDT 2010
On 08/11/2010 10:03 AM, Michael Monnerie wrote:
> On Dienstag, 10. August 2010 Peter Niemayer wrote:
>> 17% performance increase for our benchmark scenario
> Can you say what kind of data accesses you have?
The application basically writes a large data set to ~ 100,000 files,
which consists of many small messages. Each message consists of a
primary key (an integer in the range of 0 to approx. 1,000,000) and
an (almost random) number of data bytes (length in the range from 10 to
For each message, the application opens the file that is determined by
the primary key with O_APPEND, write()s the data bytes to the file.
Then it closes the file. (There are usually a few to many messages per
primary key / file).
The application runs 4 threads in parallel to spread the above action
over 4 CPU cores, each thread processes a quarter of the primary keys
(primary_key & 0x03).
This description is, of course, somewhat simplified, but it should
get you an idea on the kind of I/O-operations.
More information about the xfs