-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
I've attempted to answer the question does 1000Hz hurt responsiveness in 2.5
as much as I've found in 2.4; since subjectively the difference wasn't there
in 2.5. Using the same config with preempt enabled here are results from
2.5.70-mm3 set at default 1000Hz and at 100Hz (mm31):
no_load:
Kernel [runs] Time CPU% Loads LCPU% Ratio
2.5.70-mm3 1 79 94.9 0.0 0.0 1.00
2.5.70-mm31 1 77 94.8 0.0 0.0 1.00
cacherun:
Kernel [runs] Time CPU% Loads LCPU% Ratio
2.5.70-mm3 1 76 97.4 0.0 0.0 0.96
2.5.70-mm31 1 74 98.6 0.0 0.0 0.96
process_load:
Kernel [runs] Time CPU% Loads LCPU% Ratio
2.5.70-mm3 2 108 68.5 64.5 28.7 1.37
2.5.70-mm31 2 107 69.2 67.0 29.0 1.39
ctar_load:
Kernel [runs] Time CPU% Loads LCPU% Ratio
2.5.70-mm3 3 114 70.2 1.0 5.3 1.44
2.5.70-mm31 3 105 73.3 0.7 3.8 1.36
xtar_load:
Kernel [runs] Time CPU% Loads LCPU% Ratio
2.5.70-mm3 3 123 62.6 2.3 5.7 1.56
2.5.70-mm31 3 122 61.5 2.0 4.9 1.58
io_load:
Kernel [runs] Time CPU% Loads LCPU% Ratio
2.5.70-mm3 4 116 66.4 40.6 18.8 1.47
2.5.70-mm31 4 114 65.8 41.0 19.3 1.48
io_other:
Kernel [runs] Time CPU% Loads LCPU% Ratio
2.5.70-mm3 2 116 66.4 50.0 22.2 1.47
2.5.70-mm31 2 112 67.9 46.1 21.4 1.45
read_load:
Kernel [runs] Time CPU% Loads LCPU% Ratio
2.5.70-mm3 2 104 75.0 8.2 5.8 1.32
2.5.70-mm31 2 100 76.0 7.5 7.0 1.30
list_load:
Kernel [runs] Time CPU% Loads LCPU% Ratio
2.5.70-mm3 2 95 80.0 0.0 7.4 1.20
2.5.70-mm31 2 92 82.6 0.0 5.4 1.19
mem_load:
Kernel [runs] Time CPU% Loads LCPU% Ratio
2.5.70-mm3 2 98 80.6 53.0 2.0 1.24
2.5.70-mm31 2 95 81.1 53.0 2.1 1.23
dbench_load:
Kernel [runs] Time CPU% Loads LCPU% Ratio
2.5.70-mm3 4 313 24.3 5.0 56.9 3.96
2.5.70-mm31 4 297 24.9 4.5 52.5 3.86
At first glance everything looks faster at 100Hz. However it is well known
that it will take slightly longer even with no load at 1000Hz. Taking that
into consideration and looking more at the final ratios than the absolute
numbers it is apparent that the difference is statistically insignificant,
except on ctar_load.
Previously I had benchmark results on 1000Hz which showed preempt improved the
results in a few of the loads. For my next experiment I will compare 100Hz
with preempt to 100Hz without.
Con
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.1 (GNU/Linux)
iD8DBQE+3BRIF6dfvkL3i1gRAnEbAKCpaj/kajzKV3qVrWGRIhOh+Q8O8gCfZp6c
M3Iq1D/41t+4SB2jtNYQc48=
=NMfC
-----END PGP SIGNATURE-----
On Tue, 3 Jun 2003, Con Kolivas wrote:
> I've attempted to answer the question does 1000Hz hurt responsiveness in 2.5
> as much as I've found in 2.4; since subjectively the difference wasn't there
> in 2.5. Using the same config with preempt enabled here are results from
> 2.5.70-mm3 set at default 1000Hz and at 100Hz (mm31):
Thanks for carrying out these =)
> ctar_load:
> Kernel [runs] Time CPU% Loads LCPU% Ratio
> 2.5.70-mm3 3 114 70.2 1.0 5.3 1.44
> 2.5.70-mm31 3 105 73.3 0.7 3.8 1.36
> dbench_load:
> Kernel [runs] Time CPU% Loads LCPU% Ratio
> 2.5.70-mm3 4 313 24.3 5.0 56.9 3.96
> 2.5.70-mm31 4 297 24.9 4.5 52.5 3.86
>
> At first glance everything looks faster at 100Hz. However it is well known
> that it will take slightly longer even with no load at 1000Hz. Taking that
> into consideration and looking more at the final ratios than the absolute
> numbers it is apparent that the difference is statistically insignificant,
> except on ctar_load.
What about dbench_load?
> Previously I had benchmark results on 1000Hz which showed preempt improved the
> results in a few of the loads. For my next experiment I will compare 100Hz
> with preempt to 100Hz without.
Cheers,
Zwane
--
function.linuxpower.ca
Well thats nice, AS holds up OK...
Con Kolivas wrote:
>-----BEGIN PGP SIGNED MESSAGE-----
>Hash: SHA1
>
>I've attempted to answer the question does 1000Hz hurt responsiveness in 2.5
>as much as I've found in 2.4; since subjectively the difference wasn't there
>in 2.5. Using the same config with preempt enabled here are results from
>2.5.70-mm3 set at default 1000Hz and at 100Hz (mm31):
>
>no_load:
>Kernel [runs] Time CPU% Loads LCPU% Ratio
>2.5.70-mm3 1 79 94.9 0.0 0.0 1.00
>2.5.70-mm31 1 77 94.8 0.0 0.0 1.00
>cacherun:
>Kernel [runs] Time CPU% Loads LCPU% Ratio
>2.5.70-mm3 1 76 97.4 0.0 0.0 0.96
>2.5.70-mm31 1 74 98.6 0.0 0.0 0.96
>process_load:
>Kernel [runs] Time CPU% Loads LCPU% Ratio
>2.5.70-mm3 2 108 68.5 64.5 28.7 1.37
>2.5.70-mm31 2 107 69.2 67.0 29.0 1.39
>ctar_load:
>Kernel [runs] Time CPU% Loads LCPU% Ratio
>2.5.70-mm3 3 114 70.2 1.0 5.3 1.44
>2.5.70-mm31 3 105 73.3 0.7 3.8 1.36
>xtar_load:
>Kernel [runs] Time CPU% Loads LCPU% Ratio
>2.5.70-mm3 3 123 62.6 2.3 5.7 1.56
>2.5.70-mm31 3 122 61.5 2.0 4.9 1.58
>io_load:
>Kernel [runs] Time CPU% Loads LCPU% Ratio
>2.5.70-mm3 4 116 66.4 40.6 18.8 1.47
>2.5.70-mm31 4 114 65.8 41.0 19.3 1.48
>io_other:
>Kernel [runs] Time CPU% Loads LCPU% Ratio
>2.5.70-mm3 2 116 66.4 50.0 22.2 1.47
>2.5.70-mm31 2 112 67.9 46.1 21.4 1.45
>read_load:
>Kernel [runs] Time CPU% Loads LCPU% Ratio
>2.5.70-mm3 2 104 75.0 8.2 5.8 1.32
>2.5.70-mm31 2 100 76.0 7.5 7.0 1.30
>list_load:
>Kernel [runs] Time CPU% Loads LCPU% Ratio
>2.5.70-mm3 2 95 80.0 0.0 7.4 1.20
>2.5.70-mm31 2 92 82.6 0.0 5.4 1.19
>mem_load:
>Kernel [runs] Time CPU% Loads LCPU% Ratio
>2.5.70-mm3 2 98 80.6 53.0 2.0 1.24
>2.5.70-mm31 2 95 81.1 53.0 2.1 1.23
>dbench_load:
>Kernel [runs] Time CPU% Loads LCPU% Ratio
>2.5.70-mm3 4 313 24.3 5.0 56.9 3.96
>2.5.70-mm31 4 297 24.9 4.5 52.5 3.86
>
>At first glance everything looks faster at 100Hz. However it is well known
>that it will take slightly longer even with no load at 1000Hz. Taking that
>into consideration and looking more at the final ratios than the absolute
>numbers it is apparent that the difference is statistically insignificant,
>except on ctar_load.
>
>Previously I had benchmark results on 1000Hz which showed preempt improved the
>results in a few of the loads. For my next experiment I will compare 100Hz
>with preempt to 100Hz without.
>
>Con
>-----BEGIN PGP SIGNATURE-----
>Version: GnuPG v1.2.1 (GNU/Linux)
>
>iD8DBQE+3BRIF6dfvkL3i1gRAnEbAKCpaj/kajzKV3qVrWGRIhOh+Q8O8gCfZp6c
>M3Iq1D/41t+4SB2jtNYQc48=
>=NMfC
>-----END PGP SIGNATURE-----
>
>-
>To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>the body of a message to [email protected]
>More majordomo info at http://vger.kernel.org/majordomo-info.html
>Please read the FAQ at http://www.tux.org/lkml/
>
>
>
On 03-Jun-2003 Con Kolivas wrote:
> I've attempted to answer the question does 1000Hz hurt responsiveness in 2.5
> as much as I've found in 2.4; since subjectively the difference wasn't there
> in 2.5. Using the same config with preempt enabled here are results from
> 2.5.70-mm3 set at default 1000Hz and at 100Hz (mm31):
Is there any problem using a frequency other than 100 and 1000Hz ?
Bye.
On Tue, 3 Jun 2003 18:00, Giuliano Pochini wrote:
> On 03-Jun-2003 Con Kolivas wrote:
> > I've attempted to answer the question does 1000Hz hurt responsiveness in
> > 2.5 as much as I've found in 2.4; since subjectively the difference
> > wasn't there in 2.5. Using the same config with preempt enabled here are
> > results from 2.5.70-mm3 set at default 1000Hz and at 100Hz (mm31):
>
> Is there any problem using a frequency other than 100 and 1000Hz ?
Not at all. These were chosen because they were the default 2.4 (100) and 2.5
(1000) frequencies. The large difference in Hz was postulated to increase the
in-kernel overhead and the amount of time spent tearing down and building up
the cpu cache again. 2.4 running at 1000Hz shows poor performance at high
(>4) loads whereas 2.5 doesn't seem to do this. I originally thought it was
cache thrashing/trashing responsible. However since 2.5 performance is almost
comparable at 100/1000 it seems to be that the pure interrupt overhead in 2.5
is lower?
Con
On Tue, 3 Jun 2003 18:00, Giuliano Pochini wrote:
>> Is there any problem using a frequency other than 100 and 1000Hz ?
On Tue, Jun 03, 2003 at 08:36:49PM +1000, Con Kolivas wrote:
> Not at all. These were chosen because they were the default 2.4 (100) and 2.5
> (1000) frequencies. The large difference in Hz was postulated to increase the
> in-kernel overhead and the amount of time spent tearing down and building up
> the cpu cache again. 2.4 running at 1000Hz shows poor performance at high
> (>4) loads whereas 2.5 doesn't seem to do this. I originally thought it was
> cache thrashing/trashing responsible. However since 2.5 performance is almost
> comparable at 100/1000 it seems to be that the pure interrupt overhead in 2.5
> is lower?
You could try profiling cache misses etc.
I blame count_active_tasks(). =)
-- wli