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[Qemu-devel] [RFC PATCH 0/6] option to not remove files inside -mem-path
From: |
Eduardo Habkost |
Subject: |
[Qemu-devel] [RFC PATCH 0/6] option to not remove files inside -mem-path dir (v2) |
Date: |
Mon, 2 Jul 2012 15:06:32 -0300 |
Resending series, after fixing some coding style issues. Does anybody has any
feedback about this proposal?
Changes v1 -> v2:
- Coding style fixes
Original cover letter:
I was investigating if there are any mechanisms that allow manually pinning of
guest RAM to specific host NUMA nodes, in the case of multi-node KVM guests, and
noticed that -mem-path could be used for that, except that it currently removes
any files it creates (using mkstemp()) immediately, not allowing numactl to be
used on the backing files, as a result. This patches add a -keep-mem-path-files
option to make QEMU create the files inside -mem-path with more predictable
names, and not remove them after creation.
Some previous discussions about the subject, for reference:
- Message-ID: <address@hidden>
http://article.gmane.org/gmane.comp.emulators.kvm.devel/57684
- Message-ID: <address@hidden>
http://article.gmane.org/gmane.comp.emulators.kvm.devel/58835
A more recent thread can be found at:
- Message-ID: <address@hidden>
http://article.gmane.org/gmane.comp.emulators.qemu/123001
Note that this is just a mechanism to facilitate manual static binding using
numactl on hugetlbfs later, for optimization. This may be especially useful for
single large multi-node guests use-cases (and, of course, has to be used with
care).
I don't know if it is a good idea to use the memory range names as a publicly-
visible interface. Another option may be to use a single file instead, and mmap
different regions inside the same file for each memory region. I an open to
comments and suggestions.
Example (untested) usage to bind manually each half of the RAM of a guest to a
different NUMA node:
$ qemu-system-x86_64 [...] -m 2048 -smp 4 \
-numa node,cpus=0-1,mem=1024 -numa node,cpus=2-3,mem=1024 \
-mem-prealloc -keep-mem-path-files -mem-path /mnt/hugetlbfs/FOO
$ numactl --offset=1G --length=1G --membind=1 --file /mnt/hugetlbfs/FOO/pc.ram
$ numactl --offset=0 --length=1G --membind=2 --file /mnt/hugetlbfs/FOO/pc.ram
Eduardo Habkost (6):
file_ram_alloc(): coding style fixes
file_ram_alloc(): use g_strdup_printf() instead of asprintf()
vl.c: change mem_prealloc to bool (v2)
file_ram_alloc: change length argument to size_t (v2)
file_ram_alloc(): extract temporary-file creation code to separate
function (v2)
add -keep-mem-path-files option (v2)
cpu-all.h | 3 ++-
exec.c | 68 +++++++++++++++++++++++++++++++++++++++++++------------
qemu-options.hx | 12 ++++++++++
vl.c | 9 ++++++--
4 files changed, 75 insertions(+), 17 deletions(-)
--
1.7.10.4
- [Qemu-devel] [RFC PATCH 0/6] option to not remove files inside -mem-path dir (v2),
Eduardo Habkost <=
- [Qemu-devel] [PATCH 1/6] file_ram_alloc(): coding style fixes, Eduardo Habkost, 2012/07/02
- [Qemu-devel] [PATCH 4/6] file_ram_alloc: change length argument to size_t (v2), Eduardo Habkost, 2012/07/02
- [Qemu-devel] [RFC PATCH 6/6] add -keep-mem-path-files option (v2), Eduardo Habkost, 2012/07/02
- [Qemu-devel] [PATCH 2/6] file_ram_alloc(): use g_strdup_printf() instead of asprintf(), Eduardo Habkost, 2012/07/02
- [Qemu-devel] [PATCH 3/6] vl.c: change mem_prealloc to bool (v2), Eduardo Habkost, 2012/07/02
- [Qemu-devel] [PATCH 5/6] file_ram_alloc(): extract temporary-file creation code to separate function (v2), Eduardo Habkost, 2012/07/02
- Re: [Qemu-devel] [RFC PATCH 0/6] option to not remove files inside -mem-path dir (v2), Daniel P. Berrange, 2012/07/02