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Re: [Xen-devel] [PATCH] Getting and setting SEDF scheduling parameters

Subject: Re: [Xen-devel] [PATCH] Getting and setting SEDF scheduling parameters
From: Stephan Diestelhorst <sd386@xxxxxxxxxxxx>
Date: Thu, 12 Jan 2006 08:45:52 +0100
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Thanks for that,
I'll have a look at it!


John L Griffin wrote:

Here is a new patch to reflect Keir's directions from last Friday. Note that the patch only addresses the GET/PUT_INFO logic (not the correctness of the scheduler proper) but the scheduler seems to indeed be doing the right thing.

This patch:

1. Fixes an underflow bug in sedf_adjust_weights() that would cause the <slice> for a weight-driven domain to be set to a really big number if the CPU was already overcommitted.

2. Clarifies the logic in sedf_adjdom(). Whenever (weight==0), time-driven scheduling is selected. Otherwise, weight-driven scheduling is selected. Extratime scheduling works for both modes. [Note to Keir: in re your question, real-time weights only divvy up the spare non-time-sliced time according to the predetermined schedule.]

3. Adds a heap of comments to the code, including five examples of how one might set the scheduling parameters. Each of the five examples has been non-rigorously tested to work as described, but additional testing is warranted.

One additional change I recommend is to add printk()'s to sedf_adjdom() that indicate the failure of a scheduling operation, and possibly to indicate success as well, but that's not included in this patch.

Signed-off-by: jlg@xxxxxxxxxx


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