e1000: add interrupt mitigation support

This patch partially implements the e1000 interrupt mitigation mechanisms.
Using a single QEMUTimer, it emulates the ITR register (which is the newer
mitigation register, recommended by Intel) and approximately emulates
RADV and TADV registers. TIDV and RDTR register functionalities are not
emulated (RDTR is only used to validate RADV, according to the e1000 specs).

RADV, TADV, TIDV and RDTR registers make up the older e1000 mitigation
mechanism and would need a timer each to be completely emulated. However,
a single timer has been used in order to reach a good compromise between
emulation accuracy and simplicity/efficiency.

The implemented mechanism can be enabled/disabled specifying the command
line e1000-specific boolean parameter "mitigation", e.g.

    qemu-system-x86_64 -device e1000,mitigation=on,... ...

For more information, see the Software developer's manual at
http://download.intel.com/design/network/manuals/8254x_GBe_SDM.pdf.

Interrupt mitigation boosts performance when the guest suffers from
an high interrupt rate (i.e. receiving short UDP packets at high packet
rate). For some numerical results see the following link
http://info.iet.unipi.it/~luigi/papers/20130520-rizzo-vm.pdf

Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
Reviewed-by: Andreas Färber <afaerber@suse.de> (for pc-* machines)
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
4 files changed
tree: 88eb3ec1f4c96fdf60da56cba771874a7cecd136
  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. libcacard/
  14. linux-headers/
  15. linux-user/
  16. net/
  17. pc-bios/
  18. po/
  19. qapi/
  20. qga/
  21. QMP/
  22. qobject/
  23. qom/
  24. roms/
  25. scripts/
  26. slirp/
  27. stubs/
  28. sysconfigs/
  29. target-alpha/
  30. target-arm/
  31. target-cris/
  32. target-i386/
  33. target-lm32/
  34. target-m68k/
  35. target-microblaze/
  36. target-mips/
  37. target-moxie/
  38. target-openrisc/
  39. target-ppc/
  40. target-s390x/
  41. target-sh4/
  42. target-sparc/
  43. target-unicore32/
  44. target-xtensa/
  45. tcg/
  46. tests/
  47. trace/
  48. ui/
  49. util/
  50. .exrc
  51. .gitignore
  52. .gitmodules
  53. .mailmap
  54. aio-posix.c
  55. aio-win32.c
  56. arch_init.c
  57. async.c
  58. balloon.c
  59. block-migration.c
  60. block.c
  61. blockdev-nbd.c
  62. blockdev.c
  63. blockjob.c
  64. bt-host.c
  65. bt-vhci.c
  66. Changelog
  67. CODING_STYLE
  68. configure
  69. COPYING
  70. COPYING.LIB
  71. coroutine-gthread.c
  72. coroutine-sigaltstack.c
  73. coroutine-ucontext.c
  74. coroutine-win32.c
  75. cpu-exec.c
  76. cpus.c
  77. cputlb.c
  78. device-hotplug.c
  79. device_tree.c
  80. disas.c
  81. dma-helpers.c
  82. dump.c
  83. exec.c
  84. gdbstub.c
  85. HACKING
  86. hmp-commands.hx
  87. hmp.c
  88. hmp.h
  89. iohandler.c
  90. ioport.c
  91. kvm-all.c
  92. kvm-stub.c
  93. LICENSE
  94. main-loop.c
  95. MAINTAINERS
  96. Makefile
  97. Makefile.objs
  98. Makefile.target
  99. memory.c
  100. memory_mapping.c
  101. migration-exec.c
  102. migration-fd.c
  103. migration-rdma.c
  104. migration-tcp.c
  105. migration-unix.c
  106. migration.c
  107. monitor.c
  108. nbd.c
  109. os-posix.c
  110. os-win32.c
  111. page_cache.c
  112. qapi-schema.json
  113. qdev-monitor.c
  114. qdict-test-data.txt
  115. qemu-bridge-helper.c
  116. qemu-char.c
  117. qemu-coroutine-io.c
  118. qemu-coroutine-lock.c
  119. qemu-coroutine-sleep.c
  120. qemu-coroutine.c
  121. qemu-doc.texi
  122. qemu-img-cmds.hx
  123. qemu-img.c
  124. qemu-img.texi
  125. qemu-io-cmds.c
  126. qemu-io.c
  127. qemu-log.c
  128. qemu-nbd.c
  129. qemu-nbd.texi
  130. qemu-options-wrapper.h
  131. qemu-options.h
  132. qemu-options.hx
  133. qemu-seccomp.c
  134. qemu-tech.texi
  135. qemu-timer.c
  136. qemu.nsi
  137. qemu.sasl
  138. qmp-commands.hx
  139. qmp.c
  140. qtest.c
  141. readline.c
  142. README
  143. rules.mak
  144. savevm.c
  145. spice-qemu-char.c
  146. tcg-runtime.c
  147. tci.c
  148. thread-pool.c
  149. thunk.c
  150. tpm.c
  151. trace-events
  152. translate-all.c
  153. translate-all.h
  154. user-exec.c
  155. VERSION
  156. version.rc
  157. vl.c
  158. xbzrle.c
  159. xen-all.c
  160. xen-mapcache.c
  161. xen-stub.c