From mboxrd@z Thu Jan  1 00:00:00 1970
From: Olaf Hering <olaf@aepfle.de>
Subject: Re: [PATCH] xenpaging:add a new array to speed up
 page-in in xenpaging
Date: Tue, 10 Jan 2012 18:39:57 +0100
Message-ID: <20120110173956.GA2213@aepfle.de>
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To: Hongkaixing <hongkaixing@huawei.com>
Cc: "'bicky.'" <bicky.shi@huawei.com>, xen-devel@lists.xensource.com, 'Ian Jackson' <Ian.Jackson@eu.citrix.com>
List-Id: xen-devel@lists.xenproject.org

On Fri, Jan 06, Hongkaixing wrote:

> > Why wrap this up in a struct ?
> 
> We want to keep the same style with
> 
> typedef struct xenpaging_victim {
>     /* the gfn of the page to evict */
>     unsigned long gfn;
> } xenpaging_victim_t;

This dates back to the initial implementation of xenpaging.

In my testing I started a guest paused, paged it all out, and paged all
back into memory. By monitoring nr_pages I noticed that page-in got
slightly slower over time, so your suggestion to use two indexes will
speed things up a bit.


Looking through xenpaging.c, I think its best to have two flat arrays:
unsigned long slot_to_gfn[paging->max_pages]; /* was victims */
int gfn_to_slot[paging->max_pages];

I will prepare a patch to implement this.

Olaf