ia64/linux-2.6.18-xen.hg

view arch/mips/boot/addinitrd.c @ 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
children
line source
1 /*
2 * addinitrd - program to add a initrd image to an ecoff kernel
3 *
4 * (C) 1999 Thomas Bogendoerfer
5 * minor modifications, cleanup: Guido Guenther <agx@sigxcpu.org>
6 * further cleanup: Maciej W. Rozycki
7 */
9 #include <sys/types.h>
10 #include <sys/stat.h>
11 #include <fcntl.h>
12 #include <unistd.h>
13 #include <stdio.h>
14 #include <netinet/in.h>
16 #include "ecoff.h"
18 #define MIPS_PAGE_SIZE 4096
19 #define MIPS_PAGE_MASK (MIPS_PAGE_SIZE-1)
21 #define swab16(x) \
22 ((unsigned short)( \
23 (((unsigned short)(x) & (unsigned short)0x00ffU) << 8) | \
24 (((unsigned short)(x) & (unsigned short)0xff00U) >> 8) ))
26 #define swab32(x) \
27 ((unsigned int)( \
28 (((unsigned int)(x) & (unsigned int)0x000000ffUL) << 24) | \
29 (((unsigned int)(x) & (unsigned int)0x0000ff00UL) << 8) | \
30 (((unsigned int)(x) & (unsigned int)0x00ff0000UL) >> 8) | \
31 (((unsigned int)(x) & (unsigned int)0xff000000UL) >> 24) ))
33 #define SWAB(a) (swab ? swab32(a) : (a))
35 void die (char *s)
36 {
37 perror (s);
38 exit (1);
39 }
41 int main (int argc, char *argv[])
42 {
43 int fd_vmlinux,fd_initrd,fd_outfile;
44 FILHDR efile;
45 AOUTHDR eaout;
46 SCNHDR esecs[3];
47 struct stat st;
48 char buf[1024];
49 unsigned long loadaddr;
50 unsigned long initrd_header[2];
51 int i,cnt;
52 int swab = 0;
54 if (argc != 4) {
55 printf ("Usage: %s <vmlinux> <initrd> <outfile>\n",argv[0]);
56 exit (1);
57 }
59 if ((fd_vmlinux = open (argv[1],O_RDONLY)) < 0)
60 die ("open vmlinux");
61 if (read (fd_vmlinux, &efile, sizeof efile) != sizeof efile)
62 die ("read file header");
63 if (read (fd_vmlinux, &eaout, sizeof eaout) != sizeof eaout)
64 die ("read aout header");
65 if (read (fd_vmlinux, esecs, sizeof esecs) != sizeof esecs)
66 die ("read section headers");
67 /*
68 * check whether the file is good for us
69 */
70 /* TBD */
72 /*
73 * check, if we have to swab words
74 */
75 if (ntohs(0xaa55) == 0xaa55) {
76 if (efile.f_magic == swab16(MIPSELMAGIC))
77 swab = 1;
78 } else {
79 if (efile.f_magic == swab16(MIPSEBMAGIC))
80 swab = 1;
81 }
83 /* make sure we have an empty data segment for the initrd */
84 if (eaout.dsize || esecs[1].s_size) {
85 fprintf (stderr, "Data segment not empty. Giving up!\n");
86 exit (1);
87 }
88 if ((fd_initrd = open (argv[2], O_RDONLY)) < 0)
89 die ("open initrd");
90 if (fstat (fd_initrd, &st) < 0)
91 die ("fstat initrd");
92 loadaddr = ((SWAB(esecs[2].s_vaddr) + SWAB(esecs[2].s_size)
93 + MIPS_PAGE_SIZE-1) & ~MIPS_PAGE_MASK) - 8;
94 if (loadaddr < (SWAB(esecs[2].s_vaddr) + SWAB(esecs[2].s_size)))
95 loadaddr += MIPS_PAGE_SIZE;
96 initrd_header[0] = SWAB(0x494E5244);
97 initrd_header[1] = SWAB(st.st_size);
98 eaout.dsize = esecs[1].s_size = initrd_header[1] = SWAB(st.st_size+8);
99 eaout.data_start = esecs[1].s_vaddr = esecs[1].s_paddr = SWAB(loadaddr);
101 if ((fd_outfile = open (argv[3], O_RDWR|O_CREAT|O_TRUNC,0666)) < 0)
102 die ("open outfile");
103 if (write (fd_outfile, &efile, sizeof efile) != sizeof efile)
104 die ("write file header");
105 if (write (fd_outfile, &eaout, sizeof eaout) != sizeof eaout)
106 die ("write aout header");
107 if (write (fd_outfile, esecs, sizeof esecs) != sizeof esecs)
108 die ("write section headers");
109 /* skip padding */
110 if(lseek(fd_vmlinux, SWAB(esecs[0].s_scnptr), SEEK_SET) == (off_t)-1)
111 die ("lseek vmlinux");
112 if(lseek(fd_outfile, SWAB(esecs[0].s_scnptr), SEEK_SET) == (off_t)-1)
113 die ("lseek outfile");
114 /* copy text segment */
115 cnt = SWAB(eaout.tsize);
116 while (cnt) {
117 if ((i = read (fd_vmlinux, buf, sizeof buf)) <= 0)
118 die ("read vmlinux");
119 if (write (fd_outfile, buf, i) != i)
120 die ("write vmlinux");
121 cnt -= i;
122 }
123 if (write (fd_outfile, initrd_header, sizeof initrd_header) != sizeof initrd_header)
124 die ("write initrd header");
125 while ((i = read (fd_initrd, buf, sizeof buf)) > 0)
126 if (write (fd_outfile, buf, i) != i)
127 die ("write initrd");
128 close (fd_vmlinux);
129 close (fd_initrd);
130 return 0;
131 }