view drivers/block/ida_ioctl.h @ 897:329ea0ccb344

balloon: try harder to balloon up under memory pressure.

Currently if the balloon driver is unable to increase the guest's
reservation it assumes the failure was due to reaching its full
allocation, gives up on the ballooning operation and records the limit
it reached as the "hard limit". The driver will not try again until
the target is set again (even to the same value).

However it is possible that ballooning has in fact failed due to
memory pressure in the host and therefore it is desirable to keep
attempting to reach the target in case memory becomes available. The
most likely scenario is that some guests are ballooning down while
others are ballooning up and therefore there is temporary memory
pressure while things stabilise. You would not expect a well behaved
toolstack to ask a domain to balloon to more than its allocation nor
would you expect it to deliberately over-commit memory by setting
balloon targets which exceed the total host memory.

This patch drops the concept of a hard limit and causes the balloon
driver to retry increasing the reservation on a timer in the same
manner as when decreasing the reservation.

Also if we partially succeed in increasing the reservation
(i.e. receive less pages than we asked for) then we may as well keep
those pages rather than returning them to Xen.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Fri Jun 05 14:01:20 2009 +0100 (2009-06-05)
parents 831230e53067
line source
1 /*
2 * Disk Array driver for Compaq SMART2 Controllers
3 * Copyright 1998 Compaq Computer Corporation
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * NON INFRINGEMENT. See the GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18 *
19 * Questions/Comments/Bugfixes to iss_storagedev@hp.com
20 *
21 */
22 #ifndef IDA_IOCTL_H
23 #define IDA_IOCTL_H
25 #include "ida_cmd.h"
26 #include "cpqarray.h"
28 #define IDAGETDRVINFO 0x27272828
29 #define IDAPASSTHRU 0x28282929
30 #define IDAGETCTLRSIG 0x29293030
31 #define IDAREVALIDATEVOLS 0x30303131
32 #define IDADRIVERVERSION 0x31313232
33 #define IDAGETPCIINFO 0x32323333
35 typedef struct _ida_pci_info_struct
36 {
37 unsigned char bus;
38 unsigned char dev_fn;
39 __u32 board_id;
40 } ida_pci_info_struct;
41 /*
42 * Normally, the ioctl determines the logical unit for this command by
43 * the major,minor number of the fd passed to ioctl. If you need to send
44 * a command to a different/nonexistant unit (such as during config), you
45 * can override the normal behavior by setting the unit valid bit. (Normally,
46 * it should be zero) The controller the command is sent to is still
47 * determined by the major number of the open device.
48 */
50 #define UNITVALID 0x80
51 typedef struct {
52 __u8 cmd;
53 __u8 rcode;
54 __u8 unit;
55 __u32 blk;
56 __u16 blk_cnt;
58 /* currently, sg_cnt is assumed to be 1: only the 0th element of sg is used */
59 struct {
60 void __user *addr;
61 size_t size;
62 } sg[SG_MAX];
63 int sg_cnt;
65 union ctlr_cmds {
66 drv_info_t drv;
67 unsigned char buf[1024];
69 id_ctlr_t id_ctlr;
70 drv_param_t drv_param;
71 id_log_drv_t id_log_drv;
72 id_log_drv_ext_t id_log_drv_ext;
73 sense_log_drv_stat_t sense_log_drv_stat;
74 id_phys_drv_t id_phys_drv;
75 blink_drv_leds_t blink_drv_leds;
76 sense_blink_leds_t sense_blink_leds;
77 config_t config;
78 reorder_log_drv_t reorder_log_drv;
79 label_log_drv_t label_log_drv;
80 surf_delay_t surf_delay;
81 overhead_delay_t overhead_delay;
82 mp_delay_t mp_delay;
83 scsi_param_t scsi_param;
84 } c;
85 } ida_ioctl_t;
87 #endif /* IDA_IOCTL_H */