Re: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to 3.6-rc5 on AMD chipsets - bisected

Borislav Petkov
2012-09-25T17:00:41Z

On Tue, Sep 25, 2012 at 03:17:36PM +0200, Borislav Petkov wrote:
> For example, I did some measurements a couple of days ago on Bulldozer
> of tbench with and without select_idle_sibling:

Here are updated benchmark results with your patch here:
http://marc.info/?l=linux-kernel&m=134850871822587

I think this pretty much confirms Mel's results.

tbench runs single-socket OR-B (box has 8 cores, 4 CUs) (tbench_srv localhost), tbench default settings as in debian testing

# clients 1 2 4 8 12 16
3.6-rc6+tip/auto-latest 115.91 238.571 469.606 1865.77 1863.08 1851.46
3.6-rc6+tip/auto-latest-kill select_idle_sibling(): 354.619 534.714 900.069 1969.35 1955.91 1940.84
3.6-rc6+tip/auto-latest-revert-the-revert 114.001 223.171 408.507 1771.48 1757.08 1736.12
3.6-rc7+tip/auto-latest-select_idle_sibling-lists 107.39 222.439 435.255 1659.42 1697.43 1685.92

3.6-rc6+tip/auto-latest
-----------------------
Throughput 115.91 MB/sec 1 clients 1 procs max_latency=0.296 ms
Throughput 238.571 MB/sec 2 clients 2 procs max_latency=1.296 ms
Throughput 469.606 MB/sec 4 clients 4 procs max_latency=0.340 ms
Throughput 1865.77 MB/sec 8 clients 8 procs max_latency=3.393 ms
Throughput 1863.08 MB/sec 12 clients 12 procs max_latency=0.322 ms
Throughput 1851.46 MB/sec 16 clients 16 procs max_latency=2.059 ms

3.6-rc6+tip/auto-latest-kill select_idle_sibling()
--------------------------------------------------
Throughput 354.619 MB/sec 1 clients 1 procs max_latency=0.321 ms
Throughput 534.714 MB/sec 2 clients 2 procs max_latency=2.651 ms
Throughput 900.069 MB/sec 4 clients 4 procs max_latency=10.823 ms
Throughput 1969.35 MB/sec 8 clients 8 procs max_latency=1.630 ms
Throughput 1955.91 MB/sec 12 clients 12 procs max_latency=3.236 ms
Throughput 1940.84 MB/sec 16 clients 16 procs max_latency=0.314 ms

3.6-rc6+tip/auto-latest-revert-the-revert
-----------------------------------------
Throughput 114.001 MB/sec 1 clients 1 procs max_latency=0.352 ms
Throughput 223.171 MB/sec 2 clients 2 procs max_latency=0.348 ms
Throughput 408.507 MB/sec 4 clients 4 procs max_latency=0.388 ms
Throughput 1771.48 MB/sec 8 clients 8 procs max_latency=0.280 ms
Throughput 1757.08 MB/sec 12 clients 12 procs max_latency=3.280 ms
Throughput 1736.12 MB/sec 16 clients 16 procs max_latency=0.333 ms

3.6-rc7+tip/auto-latest-select_idle_sibling-lists
-------------------------------------------------
Throughput 107.39 MB/sec 1 clients 1 procs max_latency=0.372 ms
Throughput 222.439 MB/sec 2 clients 2 procs max_latency=0.345 ms
Throughput 435.255 MB/sec 4 clients 4 procs max_latency=0.346 ms
Throughput 1659.42 MB/sec 8 clients 8 procs max_latency=3.497 ms
Throughput 1697.43 MB/sec 12 clients 12 procs max_latency=3.205 ms
Throughput 1685.92 MB/sec 16 clients 16 procs max_latency=0.331 ms

--
Regards/Gruss,
Boris.