Re: [RFC PATCH 0/5] crash dump bitmap: scan memory pages in kernelto speedup kernel dump process

[Jingbai Ma]

On 03/09/2013 12:31 PM, HATAYAMA Daisuke wrote:
> From: Jingbai Ma<jingbai.ma@xxxxxx>
> Subject: Re: [RFC PATCH 0/5] crash dump bitmap: scan memory pages in kernel to speedup kernel dump process
> Date: Fri, 8 Mar 2013 18:06:31 +0800
>
> > On 03/07/2013 11:21 PM, Vivek Goyal wrote:
> > > On Thu, Mar 07, 2013 at 10:58:18PM +0800, Jingbai Ma wrote:
> ...
> > > First of all 64MB per TB should not be a huge deal. And makedumpfile
> > > also has this cyclic mode where you process a map, discard it and then
> > > move on to next section. So memory usage remains constant at the
> > > expense
> > > of processing time.
> >
> > Yes, that's true. But in cyclic mode, makedumpfile will have to
> > write/read bitmap from storage, it will also impact the performance.
> > I have measured the penalty for cyclic mode is about 70%
> > slowdown. Maybe could be faster after mmap implemented.
>
> I guess the slowdown came from the issue that enough VMCOREINFO was
> not provided from the kernel, and unnecessary filtering processing for
> free pages is done multiple times.

Thanks for your comments! It would be very helpful.
I will test it on the machine again.

--
Jingbai Ma (jingbai.ma@xxxxxx)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/