From a32704cf7f6c9032418837acf04e786ddbeb6c50 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ciro=20Santilli=20=E5=85=AD=E5=9B=9B=E4=BA=8B=E4=BB=B6=20?= =?UTF-8?q?=E6=B3=95=E8=BD=AE=E5=8A=9F?= Date: Wed, 6 Feb 2019 00:00:02 +0000 Subject: [PATCH] gem5: document kernel boot speedup --- README.adoc | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/README.adoc b/README.adoc index e33a72a..0afedc3 100644 --- a/README.adoc +++ b/README.adoc @@ -10201,6 +10201,18 @@ It is obviously not possible to understand what they actually do from their comm * `drm: Add component-aware simple encoder` allows you to see images through VNC: <> * `gem5: Add support for gem5's extended GIC mode` adds support for more than 8 cores: <> +==== gem5 arm Linux kernel patches boot speedup + +We have observed that with the kernel patches, boot is 2x faster, falling from 1m40s to 50s. + +With link:https://stackoverflow.com/questions/49797246/how-to-monitor-for-how-much-time-each-line-of-stdout-was-the-last-output-line-in/49797547#49797547[`ts`], we see that a large part of the difference is at the message: + +.... +clocksource: Switched to clocksource arch_sys_counter +.... + +which takes 4s on the patched kernel, and 30s on the unpatched one! TODO understand why, especially if it is a config difference, or if it actually comes from a patch. + === m5out directory When you run gem5, it generates an `m5out` directory at: