ext2/3 performance regression in 2.6 vs 2.4 for small interleaved writes

ext2/3 performance regression in 2.6 vs 2.4 for small interleaved writes

Post by Michael Fr » Fri, 13 Feb 2004 06:00:15



2.4 has a deadline scheduler. 2.6 default is anticipatory.

Could you please boot with scheduler=deadline to compare apples with apples.

Regards
Michael


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ext2/3 performance regression in 2.6 vs 2.4 for small interleaved writes

Post by Dave Olie » Fri, 13 Feb 2004 11:10:04


2.4 does not have deadline scheduler. But the 2.6 deadline scheduler
is more similar to 2.4's scheduler than is the anticipatory scheduler.

Re-try 2.6 with deadline scheduler will remove some of the additional
scheduler policies that are present in the anticipatory scheduler.


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ext2/3 performance regression in 2.6 vs 2.4 for small interleaved writes

Post by Andrea Arc » Fri, 13 Feb 2004 11:30:10


the main difference is that 2.4 isn't in function of time, it's in
function of requests, no matter how long it takes to write a request, so
it's potentially optimizing slow devices when you don't care about
latency (deadline can be tuned for each dev via
/sys/block/*/queue/iosched/).
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ext2/3 performance regression in 2.6 vs 2.4 for small interleaved writes

Post by Alex Zaroc » Wed, 18 Feb 2004 03:00:20

n Thu, Feb 12, 2004 at 08:20:46PM +0000, Jon Burgess wrote:

I ran slow.c on Reiser4, it is different hardware, ext2 results are for
comparing:

server config:
2xXeon, hyperthreading, 256 MB RAM
Linux-2.6.2

Test:
/tests/slow foo 1024
it writes 1GB to one or two files.

Results:
---------+------------+-----------+-----------+-----------+
| 1 stream | 2 streams |
---------+------------+-----------+-----------+-----------+
| WRITE | READ | WRITE | READ |
---------+------------+-----------+-----------+-----------+
REISER4 | 33.67 Mb/s | 40.97Mb/s | 30.78Mb/s | 38.37Mb/s |
---------+------------+-----------+-----------+-----------+
EXT2 | 33.32Mb/s | 40.82Mb/s | 9.45Mb/s | 20.39Mb/s |
---------+------------+-----------+-----------+-----------+

The fs with delayed block allocation (Reiser4, XFS, seems JFS too) look much
better.


--
Alex.
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