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/******************************************************************************
*
* Xen domain paging default policy.
*
* Copyright (c) 2009 Citrix Systems, Inc. (Patrick Colp)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "xc_bitops.h"
#include "policy.h"
#define DEFAULT_MRU_SIZE (1024 * 16)
static unsigned long *mru;
static unsigned int i_mru;
static unsigned int mru_size;
static unsigned long *bitmap;
static unsigned long *unconsumed;
static unsigned long current_gfn;
static unsigned long max_pages;
int policy_init(xenpaging_t *paging)
{
int i;
int rc = -ENOMEM;
/* Allocate bitmap for pages not to page out */
bitmap = bitmap_alloc(paging->domain_info->max_pages);
if ( !bitmap )
goto out;
/* Allocate bitmap to track unusable pages */
unconsumed = bitmap_alloc(paging->domain_info->max_pages);
if ( !unconsumed )
goto out;
max_pages = paging->domain_info->max_pages;
/* Initialise MRU list of paged in pages */
if ( paging->policy_mru_size > 0 )
mru_size = paging->policy_mru_size;
else
mru_size = DEFAULT_MRU_SIZE;
mru = malloc(sizeof(*mru) * mru_size);
if ( mru == NULL )
goto out;
for ( i = 0; i < mru_size; i++ )
mru[i] = INVALID_MFN;
/* Don't page out page 0 */
set_bit(0, bitmap);
/* Start in the middle to avoid paging during BIOS startup */
current_gfn = max_pages / 2;
current_gfn -= paging->num_pages / 2;
rc = 0;
out:
return rc;
}
int policy_choose_victim(xenpaging_t *paging, xenpaging_victim_t *victim)
{
xc_interface *xch = paging->xc_handle;
unsigned long wrap = current_gfn;
do
{
current_gfn++;
if ( current_gfn >= max_pages )
current_gfn = 0;
if ( wrap == current_gfn )
{
victim->gfn = INVALID_MFN;
return -ENOSPC;
}
}
while ( test_bit(current_gfn, bitmap) || test_bit(current_gfn, unconsumed) );
set_bit(current_gfn, unconsumed);
victim->gfn = current_gfn;
return 0;
}
void policy_notify_paged_out(unsigned long gfn)
{
set_bit(gfn, bitmap);
clear_bit(gfn, unconsumed);
}
void policy_notify_paged_in(unsigned long gfn)
{
unsigned long old_gfn = mru[i_mru & (mru_size - 1)];
if ( old_gfn != INVALID_MFN )
clear_bit(old_gfn, bitmap);
mru[i_mru & (mru_size - 1)] = gfn;
i_mru++;
}
/*
* Local variables:
* mode: C
* c-set-style: "BSD"
* c-basic-offset: 4
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/
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