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SubjectRe: 2.4.1pre8 slowdown on dbench tests
On Tuesday 23 January 2001 13:54, Jens Axboe wrote:
>
> Thanks! Could I talk you into doing one last run? pre8 with
> include/linux/elevator.h having these values set for
> ELEVATOR_LINUS:
>
Here are two sets of dbench 48 runs with that mod. I can't explain why the
second set is faster. The second set was performed with no reboot after the
first set. The individual runs were performed with no wait in-between.

Steven

2.4.1-pre8 with changes to elevator.h, first run set
average: 9.52569 MB/sec

Throughput 9.51356 MB/sec (NB=11.892 MB/sec 95.1356 MBit/sec)
Throughput 9.43096 MB/sec (NB=11.7887 MB/sec 94.3096 MBit/sec)
Throughput 9.54195 MB/sec (NB=11.9274 MB/sec 95.4195 MBit/sec)
Throughput 9.61631 MB/sec (NB=12.0204 MB/sec 96.1631 MBit/sec)

2.4.1-pre8 same as above, second run set
average: 10.1621 MB/sec

Throughput 10.1236 MB/sec (NB=12.6546 MB/sec 101.236 MBit/sec)
Throughput 10.0304 MB/sec (NB=12.5381 MB/sec 100.304 MBit/sec)
Throughput 10.1844 MB/sec (NB=12.7305 MB/sec 101.844 MBit/sec)
Throughput 10.3099 MB/sec (NB=12.8873 MB/sec 103.099 MBit/sec)

Here is the change I made to elevator.h which you suggested:

--- elevator.h.orig Wed Jan 24 07:12:00 2001
+++ elevator.h Wed Jan 24 07:12:47 2001
@@ -94,8 +94,8 @@

#define ELEVATOR_LINUS \
((elevator_t) {
\
- 8192, /* read passovers */ \
- 16384, /* write passovers */ \
+ 1000000, /* read passovers */
\
+ 2000000, /* write passovers */
\
\
elevator_linus_merge, /* elevator_merge_fn */ \
elevator_linus_merge_cleanup, /* elevator_merge_cleanup_fn */ \
-
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