Re: [PATCH 2/2] powerpc/mm: Enable page parallel initialisation
From: Li Zhang
Date: Tue Mar 08 2016 - 21:06:54 EST
On Tue, Mar 8, 2016 at 5:36 PM, Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote:
> Hi Li,
> On Tue, 2016-03-08 at 11:55 +0800, Li Zhang wrote:
>> From: Li Zhang <zhlcindy@xxxxxxxxxxxxxxxxxx>
>> Parallel initialisation has been enabled for X86, boot time is
>> improved greatly. On Power8, it is improved greatly for small
>> memory. Here is the result from my test on Power8 platform:
>> For 4GB memory: 57% is improved, boot time as the following:
>> with patch: 10s, without patch: 24.5s
> This isn't worded quite right, and the numbers are a bit off.
> old = 24.5
> new = 10
> So the improvement is 14.5 (seconds).
> That means the improvement (14.5) as a percentage of the original boot time is:
> = 14.5 / 24.5 * 100
> = 59.183673469387756
> = 59%
Oh, sorry. It seems that I made a mistake.
> So you would say:
> For 4GB of memory, boot time is improved by 59%, from 24.5s to 10s.
Got it. :)
>> For 50GB memory: 22% is improved, boot time as the following:
>> with patch: 43.8s, without patch: 56.8s
> For 50GB memory, boot time is improved by 22%, from 56.8s to 43.8s.
>> Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
>> Signed-off-by: Li Zhang <zhlcindy@xxxxxxxxxxxxxxxxxx>
>> * Add boot time details in change log.
>> * Please apply this patch after [PATCH 1/2] mm: meminit: initialise
>> more memory for inode/dentry hash tables in early boot, because
>> [PATCH 1/2] is to fix a bug which can be reproduced on Power.
> Given that, I think it would be best if Andrew merged both of these patches.
> Because this patch is pretty trivial, whereas the patch to mm/ is less so.
> Is that OK Andrew?
> For this one:
> Acked-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>