Re: [Xen-devel] [PATCH] xenpaging:add a new array to speed up page-in in xenpaging

[Olaf Hering <olaf@xxxxxxxxx>]

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

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