Sorry for delayed response.
From: Vivek Goyal <vgoyal(a)redhat.com>
Subject: Re: [RFC][PATCH] Add --split support for dump on filesystem
Date: Mon, 31 Mar 2014 08:47:12 -0400
On Mon, Mar 31, 2014 at 07:21:20PM +0900, HATAYAMA Daisuke wrote:
[..]
> Yes, I also think the design needs to be changed for multiple
> disks...
>So I'm not thinking optimistically you reacts positive
> attitude to the feature..
I am not sure what does this mean?
[..]
> >> Anyway, benchmark will be needed to discuss this topic in detail.
> >>
> >
> > Agreed. First we need to implement that new mode and see if it gives
> > us good performance or not.
> >
>
> I've already investigated the feature in processing level but I need
> some more time to make a patch set because supporting pthread need to
> change makedumpfile to a certain amount. Please wait for now.
Sure not a problem. No rush. I was just brain storming to figure out
what features are already present and what new features are required. So
atleast we agree that dumping to single file while having multiple threads
for filtering and compression is a new feature.
Till we get that feature, I guess customers can achieve that parallelism
by dumping to multiple files (to same adaptor) and then reassembling
those files manually later.
Thanks
Vivek
So, I'll post a patch to support --split patch as a means of
supporting parallelism. Do you agree with this direction?
In the patch, --split is no logner automatically inserted. User should
specify it in core_collector explicitly, and then kdump script detects
it and appends a multiple vmcore argumetns accordingly. The number of
the multiple arguments is the number of cpus running in the 2nd
kernel, i.e., the number specified in nr_cpus.
That is, if in /etc/kdump.conf core_collector is specified as
core_collector makedumpfile --split -l -d 31
and the number of online cpus on the 2nd kernel is more than 2, say 3
here, then, the following command is executed:
$ makedumpfile --split -l -d 31 /proc/vmcore vmcore-0-incomplete vmcore-1-incomplete
vmcore-2-incomplete
If makedumpfile --split is specified but the number of online cpus on
the 2nd kernel is 1, then --split is removed as makedumpfile fails
while warning that more vmcore arugments are needed.
I'll post a patch for how-to file to document this properly.
Thanks.
HATAYAMA, Daisuke