[DragonFlyBSD - Bug #2288] Random IO performance loss introduced since January 1st

Wed Jan 23 16:21:28 PST 2013

Issue #2288 has been updated by tuxillo.

Priority changed from Low to Normal

Jan,

Do you think we can have this checked again? Didn't you run this tests automatically?

Cheers,
Antonio Huete
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Bug #2288: Random IO performance loss introduced since January 1st
http://bugs.dragonflybsd.org/issues/2288

Author: lentferj
Status: Feedback
Priority: Normal
Assignee: 
Category: 
Target version: 

Running pgbench I found that performance had dropped by 13%. To figure out the reason I did some sysbench io tests (see below). All tests were run using the same test files, same hardware etc etc 3 times in a row. As the results were consistent I am only pasting the result of the last run of each set.

The cause for the performance loss must have been introduced some time between Jan 1st and Jan 23rd.

2.12:
atom# sysbench --test=fileio --file-num=8 --file-total-size=6G --file-test-mode=rndrd --max-requests=0 --max-time=300 run
sysbench 0.4.12:  multi-threaded system evaluation benchmark

Running the test with following options:
Number of threads: 1

Extra file open flags: 0
8 files, 768Mb each
6Gb total file size
Block size 16Kb
Number of random requests for random IO: 0
Read/Write ratio for combined random IO test: 1.50
Periodic FSYNC enabled, calling fsync() each 100 requests.
Calling fsync() at the end of test, Enabled.
Using synchronous I/O mode
Doing random read test
Threads started!
Time limit exceeded, exiting...
Done.

Operations performed:  50389 Read, 0 Write, 0 Other = 50389 Total
Read 787.33Mb  Written 0b  Total transferred 787.33Mb  (2.6244Mb/sec)
  167.96 Requests/sec executed

Test execution summary:
    total time:                          300.0027s
    total number of events:              50389
    total time taken by event execution: 299.7273
    per-request statistics:
         min:                                  0.02ms
         avg:                                  5.95ms
         max:                                 77.80ms
         approx.  95 percentile:              12.05ms

Threads fairness:
    events (avg/stddev):           50389.0000/0.00
    execution time (avg/stddev):   299.7273/0.00

2.13 g47f97 (new year's eve):
atom# sysbench --test=fileio --file-num=8 --file-total-size=6G --file-test-mode=rndrd --max-requests=0 --max-time=300 run
sysbench 0.4.12:  multi-threaded system evaluation benchmark

Running the test with following options:
Number of threads: 1

Extra file open flags: 0
8 files, 768Mb each
6Gb total file size
Block size 16Kb
Number of random requests for random IO: 0
Read/Write ratio for combined random IO test: 1.50
Periodic FSYNC enabled, calling fsync() each 100 requests.
Calling fsync() at the end of test, Enabled.
Using synchronous I/O mode
Doing random read test
Threads started!
Time limit exceeded, exiting...
Done.

Operations performed:  50037 Read, 0 Write, 0 Other = 50037 Total
Read 781.83Mb  Written 0b  Total transferred 781.83Mb  (2.6061Mb/sec)
  166.79 Requests/sec executed

Test execution summary:
    total time:                          300.0040s
    total number of events:              50037
    total time taken by event execution: 299.7070
    per-request statistics:
         min:                                  0.02ms
         avg:                                  5.99ms
         max:                                104.73ms
         approx.  95 percentile:              12.06ms

Threads fairness:
    events (avg/stddev):           50037.0000/0.00
    execution time (avg/stddev):   299.7070/0.00

2.13 (from Jan 23rd incl. the sili/ahci fix):
atom# sysbench --test=fileio --file-num=8 --file-total-size=6G --file-test-mode=rndrd --max-requests=0 --max-time=300 run
sysbench 0.4.12:  multi-threaded system evaluation benchmark

Running the test with following options:
Number of threads: 1

Extra file open flags: 0
8 files, 768Mb each
6Gb total file size
Block size 16Kb
Number of random requests for random IO: 0
Read/Write ratio for combined random IO test: 1.50
Periodic FSYNC enabled, calling fsync() each 100 requests.
Calling fsync() at the end of test, Enabled.
Using synchronous I/O mode
Doing random read test
Threads started!
Time limit exceeded, exiting...
Done.

Operations performed:  39898 Read, 0 Write, 0 Other = 39898 Total
Read 623.41Mb  Written 0b  Total transferred 623.41Mb  (2.078Mb/sec)
  132.99 Requests/sec executed

Test execution summary:
    total time:                          300.0038s
    total number of events:              39898
    total time taken by event execution: 299.7377
    per-request statistics:
         min:                                  0.02ms
         avg:                                  7.51ms
         max:                                 61.00ms
         approx.  95 percentile:              12.27ms

Threads fairness:
    events (avg/stddev):           39898.0000/0.00
    execution time (avg/stddev):   299.7377/0.00

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