Re: [v4 PATCH 1/2] mm: swap: check if swap backing device is congested or not
From: Daniel Jordan
Date: Wed Jan 02 2019 - 18:00:56 EST
On Sun, Dec 30, 2018 at 12:49:34PM +0800, Yang Shi wrote:
> The test on my virtual machine with congested HDD shows long tail
> latency is reduced significantly.
>
> Without the patch
> page_fault1_thr-1490 [023] 129.311706: funcgraph_entry: #57377.796 us | do_swap_page();
> page_fault1_thr-1490 [023] 129.369103: funcgraph_entry: 5.642us | do_swap_page();
> page_fault1_thr-1490 [023] 129.369119: funcgraph_entry: #1289.592 us | do_swap_page();
> page_fault1_thr-1490 [023] 129.370411: funcgraph_entry: 4.957us | do_swap_page();
> page_fault1_thr-1490 [023] 129.370419: funcgraph_entry: 1.940us | do_swap_page();
> page_fault1_thr-1490 [023] 129.378847: funcgraph_entry: #1411.385 us | do_swap_page();
> page_fault1_thr-1490 [023] 129.380262: funcgraph_entry: 3.916us | do_swap_page();
> page_fault1_thr-1490 [023] 129.380275: funcgraph_entry: #4287.751 us | do_swap_page();
>
> With the patch
> runtest.py-1417 [020] 301.925911: funcgraph_entry: #9870.146 us | do_swap_page();
> runtest.py-1417 [020] 301.935785: funcgraph_entry: 9.802us | do_swap_page();
> runtest.py-1417 [020] 301.935799: funcgraph_entry: 3.551us | do_swap_page();
> runtest.py-1417 [020] 301.935806: funcgraph_entry: 2.142us | do_swap_page();
> runtest.py-1417 [020] 301.935853: funcgraph_entry: 6.938us | do_swap_page();
> runtest.py-1417 [020] 301.935864: funcgraph_entry: 3.765us | do_swap_page();
> runtest.py-1417 [020] 301.935871: funcgraph_entry: 3.600us | do_swap_page();
> runtest.py-1417 [020] 301.935878: funcgraph_entry: 7.202us | do_swap_page();
Hi Yang, I guess runtest.py just calls page_fault1_thr? Being explicit about
this may improve the changelog for those unfamiliar with will-it-scale.
May also be useful to name will-it-scale and how it was run (#thr, runtime,
system cpus/memory/swap) for more context.