The patch titled
Subject: kexec: yield to scheduler when loading kimage segments
has been added to the -mm tree. Its filename is
kexec-yield-to-scheduler-when-loading-kimage-segments.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kexec-yield-to-scheduler-when-loading-kimage-segments.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kexec-yield-to-scheduler-when-loading-kimage-segments.patch
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------------------------------------------------------
From: Jarrett Farnitano <jmf@xxxxxxxxxx>
Subject: kexec: yield to scheduler when loading kimage segments
Without yielding while loading kimage segments, a large initrd will block
all other work on the CPU performing the load until it is completed. For
example loading an initrd of 200MB on a low power single core system will
lock up the system for a few seconds.
To increase system responsiveness to other tasks at that time, call
cond_resched() in both the crash kernel and normal kernel segment loading
loops.
I did run into a practical problem. Hardware watchdogs on embedded
systems can have short timers on the order of seconds. If the system is
locked up for a few seconds with only a single core available, the
watchdog may not be pet in a timely fashion. If this happens, the
hardware watchdog will fire and reset the system.
This really only becomes a problem when you are working with a single
core, a decently sized initrd, and have a constrained hardware watchdog.
Link: http://lkml.kernel.org/r/1528738546-3328-1-git-send-email-jmf@xxxxxxxxxx
Signed-off-by: Jarrett Farnitano <jmf@xxxxxxxxxx>
Reviewed-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/kexec_core.c | 4 ++++
1 file changed, 4 insertions(+)
diff -puN kernel/kexec_core.c~kexec-yield-to-scheduler-when-loading-kimage-segments kernel/kexec_core.c
--- a/kernel/kexec_core.c~kexec-yield-to-scheduler-when-loading-kimage-segments
+++ a/kernel/kexec_core.c
@@ -829,6 +829,8 @@ static int kimage_load_normal_segment(st
else
buf += mchunk;
mbytes -= mchunk;
+
+ cond_resched();
}
out:
return result;
@@ -893,6 +895,8 @@ static int kimage_load_crash_segment(str
else
buf += mchunk;
mbytes -= mchunk;
+
+ cond_resched();
}
out:
return result;
_
Patches currently in -mm which might be from jmf@xxxxxxxxxx are
kexec-yield-to-scheduler-when-loading-kimage-segments.patch
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