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SubjectRe: [Patch 0/9] Performance
Greg KH wrote:
> On Mon, Mar 13, 2006 at 07:40:34PM -0500, Shailabh Nagar wrote:
>
>>This is the next iteration of the delay accounting patches
>>last posted at
>>http://www.ussg.iu.edu/hypermail/linux/kernel/0602.3/0893.html
>
>
> Do you have any benchmark numbers with this patch applied and with it
> not applied? Last I heard it was a measurable decrease for some
> "important" benchmark results...
>
> thanks,
>
> greg k-h

Here are some numbers for the latest set of posted patches
using microbenchmarks hackbench, kernbench and lmbench.

I was trying to get the real/big benchmark numbers too but
it looks like getting a run whose numbers can be trusted
will take a bit longer than expected. Preliminary runs of
transaction processing benchmarks indicate that overhead
actually decreases with the patch (as also seen in some of
the lmbench numbers below).

--Shailabh



Results highlights

- Configuring delay accounting adds < 0.5%
overhead in most cases and even reduces overhead
in some cases

- Enabling delay accounting has similar results
with a maximum overhead of 1.2% for hackbench
, most other overheads < 1% and reduction in
overhead in some cases



Base
Vanilla 2.6.16-rc6 kernel
without any patches applied
+patch
Delay accounting configured
but not enabled at boot
+patch+enable
Delay accounting enabled at boot
but no stats read

Hackbench
---------
200 groups, using sockets
Elapsed time, in seconds, lower better

%Ovhd Time
Base 0 12.468
+patch 0.4% 12.523
+patch+enable 1.2% 12.622

Kernbench
---------
Average of 5 iterations
Elapsed time, in seconds, lower better

%Ovhd Elapsed
Base 0 195.776
+patch 0.2% 196.246
+patch+enable 0.3% 196.282

Lmbench
-------

Processor, Processes - times in microseconds - smaller is better
----------------------------------------------------------------
Host OS Mhz null null open selct sig sig fork exec sh
call I/O stat clos TCP inst hndl proc proc proc
--------- ------------- ---- ---- ---- ---- ---- ----- ---- ---- ---- ---- ----
base Linux 2.6.16- 2783 0.17 0.33 5.17 6.49 13.4 0.64 2.61 146. 610. 9376
+patch Linux 2.6.16- 2781 0.17 0.32 4.75 5.85 13.0 0.64 2.62 145. 628. 9393
+patch+en Linux 2.6.16- 2784 0.17 0.32 4.71 6.14 13.4 0.64 2.60 150. 616. 9402

Context switching - times in microseconds - smaller is better
-------------------------------------------------------------
Host OS 2p/0K 2p/16K 2p/64K 8p/16K 8p/64K 16p/16K 16p/64K
ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw
--------- ------------- ----- ------ ------ ------ ------ ------- -------
base Linux 2.6.16- 4.340 4.9600 7.3300 6.5700 30.3 10.4 36.0
+patch Linux 2.6.16- 4.390 4.9800 7.3100 6.5900 29.7 9.62000 35.8
+patch+en Linux 2.6.16- 4.560 5.0800 7.2400 5.6900 22.7 10.3 33.8

*Local* Communication latencies in microseconds - smaller is better
-------------------------------------------------------------------
Host OS 2p/0K Pipe AF UDP RPC/ TCP RPC/ TCP
ctxsw UNIX UDP TCP conn
--------- ------------- ----- ----- ---- ----- ----- ----- ----- ----
base Linux 2.6.16- 4.340 15.9 12.2 18.3 24.9 21.5 29.1 45.3
+patch Linux 2.6.16- 4.390 15.7 11.8 18.6 22.2 22.0 29.1 44.8
+patch+en Linux 2.6.16- 4.560 15.6 12.1 18.9 25.3 21.9 27.1 45.1

File & VM system latencies in microseconds - smaller is better
--------------------------------------------------------------
Host OS 0K File 10K File Mmap Prot Page
Create Delete Create Delete Latency Fault Fault
--------- ------------- ------ ------ ------ ------ ------- ----- -----
base Linux 2.6.16- 39.8 58.0 112.0 82.6 8417.0 0.838 2.00000
+patch Linux 2.6.16- 39.6 58.2 111.0 82.3 8392.0 0.864 2.00000
+patch+en Linux 2.6.16- 39.6 59.1 112.8 83.2 8308.0 0.821 2.00000

*Local* Communication bandwidths in MB/s - bigger is better
-----------------------------------------------------------
Host OS Pipe AF TCP File Mmap Bcopy Bcopy Mem Mem
UNIX reread reread (libc) (hand) read write
--------- ------------- ---- ---- ---- ------ ------ ------ ------ ---- -----
base Linux 2.6.16- 676. 616. 620. 1658.0 2030.6 759.6 825.9 2032 1177.
+patch Linux 2.6.16- 627. 165. 616. 1649.9 2030.9 766.1 834.1 2030 1187.
+patch+en Linux 2.6.16- 633. 148. 603. 1569.7 2030.9 757.2 835.3 2030 1174.

Memory latencies in nanoseconds - smaller is better
(WARNING - may not be correct, check graphs)
---------------------------------------------------
Host OS Mhz L1 $ L2 $ Main mem Guesses
--------- ------------- ---- ----- ------ -------- -------
base Linux 2.6.16- 2783 0.719 6.5960 110.5
+patch Linux 2.6.16- 2781 0.720 6.5980 111.0
+patch+en Linux 2.6.16- 2784 0.720 6.5970 110.7


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