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From: Chegu Vinod <chegu_vinod@hp.com>
To: Satoru Moriya <satoru.moriya@hds.com>,
	qemu-devel qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH v4] Add option to mlock qemu and guest memory
Date: Sun, 21 Apr 2013 22:16:26 -0700	[thread overview]
Message-ID: <5174C7AA.5040701@hp.com> (raw)

Hi Satoru,

FYI... I had tried to use this change earlier and it did show some 
improvements in perf. (due to reduced exits).

But as expected mlockall () on large sized guests adds a considerable 
delay in boot time. For e.g. on an 8 socket Westmere box => a 256G guest 
: took an additional ~2+ mins to boot and a 512G guest took an 
additional ~5+ mins to boot. This is mainly due to long time spent in 
trying to clear all the pages.

     77.96%         35728  qemu-system-x86  [kernel.kallsyms]     [k] 
clear_page_c
             |
             --- clear_page_c
                 hugetlb_no_page
                 hugetlb_fault
                 follow_hugetlb_page
                 __get_user_pages
                 __mlock_vma_pages_range
                 __mm_populate
                 vm_mmap_pgoff
                 sys_mmap_pgoff
                 sys_mmap
                 system_call
                 __GI___mmap64
                 qemu_ram_alloc_from_ptr
                 qemu_ram_alloc
                 memory_region_init_ram
                 pc_memory_init
                 pc_init1
                 pc_init_pci
                 main
                 __libc_start_main

Need to have a faster way to clear pages.
Vinod

             reply	other threads:[~2013-04-22  5:16 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-22  5:16 Chegu Vinod [this message]
2013-04-23  3:47 ` [Qemu-devel] [PATCH v4] Add option to mlock qemu and guest memory Satoru Moriya
  -- strict thread matches above, loose matches on Subject: below --
2013-03-26 15:05 Satoru Moriya
2013-03-27 15:18 ` Anthony Liguori
2013-03-28  4:43   ` Satoru Moriya
2013-04-02 15:03     ` Seiji Aguchi
2013-04-02 19:12       ` Anthony Liguori
2013-04-03  7:57       ` Markus Armbruster
2013-04-22 18:38 ` Anthony Liguori

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