migration: do not sent zero pages in bulk stage

during bulk stage of ram migration if a page is a
zero page do not send it at all.
the memory at the destination reads as zero anyway.

even if there is an madvise with QEMU_MADV_DONTNEED
at the target upon receipt of a zero page I have observed
that the target starts swapping if the memory is overcommitted.
it seems that the pages are dropped asynchronously.

this patch also updates QMP to return the number of
skipped pages in MigrationStats.

Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
6 files changed
tree: 9475bdb59345550bb248fad75fa25e598811fe51
  1. audio/
  2. backends/
  3. block/
  4. bsd-user/
  5. default-configs/
  6. disas/
  7. docs/
  8. fpu/
  9. fsdev/
  10. gdb-xml/
  11. hw/
  12. include/
  13. ldscripts/
  14. libcacard/
  15. linux-headers/
  16. linux-user/
  17. net/
  18. pc-bios/
  19. po/
  20. qapi/
  21. qga/
  22. QMP/
  23. qobject/
  24. qom/
  25. roms/
  26. scripts/
  27. slirp/
  28. stubs/
  29. sysconfigs/
  30. target-alpha/
  31. target-arm/
  32. target-cris/
  33. target-i386/
  34. target-lm32/
  35. target-m68k/
  36. target-microblaze/
  37. target-mips/
  38. target-moxie/
  39. target-openrisc/
  40. target-ppc/
  41. target-s390x/
  42. target-sh4/
  43. target-sparc/
  44. target-unicore32/
  45. target-xtensa/
  46. tcg/
  47. tests/
  48. tpm/
  49. trace/
  50. ui/
  51. util/
  52. .exrc
  53. .gitignore
  54. .gitmodules
  55. .mailmap
  56. aio-posix.c
  57. aio-win32.c
  58. arch_init.c
  59. async.c
  60. balloon.c
  61. block-migration.c
  62. block.c
  63. blockdev-nbd.c
  64. blockdev.c
  65. blockjob.c
  66. bt-host.c
  67. bt-vhci.c
  68. Changelog
  69. cmd.c
  70. cmd.h
  71. CODING_STYLE
  72. configure
  73. COPYING
  74. COPYING.LIB
  75. coroutine-gthread.c
  76. coroutine-sigaltstack.c
  77. coroutine-ucontext.c
  78. coroutine-win32.c
  79. cpu-exec.c
  80. cpus.c
  81. cputlb.c
  82. device-hotplug.c
  83. device_tree.c
  84. disas.c
  85. dma-helpers.c
  86. dump-stub.c
  87. dump.c
  88. exec.c
  89. gdbstub.c
  90. HACKING
  91. hmp-commands.hx
  92. hmp.c
  93. hmp.h
  94. iohandler.c
  95. ioport.c
  96. kvm-all.c
  97. kvm-stub.c
  98. LICENSE
  99. main-loop.c
  100. MAINTAINERS
  101. Makefile
  102. Makefile.objs
  103. Makefile.target
  104. memory.c
  105. memory_mapping-stub.c
  106. memory_mapping.c
  107. migration-exec.c
  108. migration-fd.c
  109. migration-tcp.c
  110. migration-unix.c
  111. migration.c
  112. monitor.c
  113. nbd.c
  114. os-posix.c
  115. os-win32.c
  116. page_cache.c
  117. qapi-schema-test.json
  118. qapi-schema.json
  119. qdev-monitor.c
  120. qdict-test-data.txt
  121. qemu-bridge-helper.c
  122. qemu-char.c
  123. qemu-coroutine-io.c
  124. qemu-coroutine-lock.c
  125. qemu-coroutine-sleep.c
  126. qemu-coroutine.c
  127. qemu-doc.texi
  128. qemu-img-cmds.hx
  129. qemu-img.c
  130. qemu-img.texi
  131. qemu-io.c
  132. qemu-log.c
  133. qemu-nbd.c
  134. qemu-nbd.texi
  135. qemu-options-wrapper.h
  136. qemu-options.h
  137. qemu-options.hx
  138. qemu-seccomp.c
  139. qemu-tech.texi
  140. qemu-timer.c
  141. qemu.sasl
  142. qmp-commands.hx
  143. qmp.c
  144. qtest.c
  145. readline.c
  146. README
  147. rules.mak
  148. savevm.c
  149. spice-qemu-char.c
  150. tcg-runtime.c
  151. tci.c
  152. thread-pool.c
  153. thunk.c
  154. trace-events
  155. translate-all.c
  156. translate-all.h
  157. user-exec.c
  158. VERSION
  159. version.rc
  160. vl.c
  161. xbzrle.c
  162. xen-all.c
  163. xen-mapcache.c
  164. xen-stub.c