From: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
To: Avi Kivity <avi@redhat.com>
Cc: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>,
mtosatti@redhat.com, kvm@vger.kernel.org
Subject: Re: [PATCH RFC 5/5] KVM: This is the main part of the "moving dirty bitmaps to user space"
Date: Tue, 13 Apr 2010 05:55:10 +0900 [thread overview]
Message-ID: <4BC388AE.9010903@oss.ntt.co.jp> (raw)
In-Reply-To: <4BC2E64E.1090202@redhat.com>
Avi Kivity wrote:
> On 04/12/2010 05:29 AM, Takuya Yoshikawa wrote:
>>>> TODO:
>>>> 1. We want to use copy_in_user() for 32bit case too.
>>>
>>> Definitely. Why doesn't it work now?
>>
>> Sadly we don't have that for 32bit. We have to implement by ourselves.
>>
>> I tested two temporary implementations for 32bit:
>> 1. This version using copy_from_user() and copy_to_user() with
>> not nice vmalloc().
>> 2. Loop with __get_user() and __put_user().
>>
>> The result was 1 is much faster than 2.
>
> What about copy_from_user()/copy_to_user() through a 512 byte buffer
> on the kernel stack?
Reserving 512 bytes on the stack looks like too much, I'd rather kmalloc
a 512 byte buffer at VM
creation time and pass it down to the dirty page tracking code. Would
you be OK with such an
approach?
next prev parent reply other threads:[~2010-04-12 21:18 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-09 9:27 [PATCH RFC 0/5] KVM: Moving dirty bitmaps to userspace: double buffering approach Takuya Yoshikawa
2010-04-09 9:30 ` [PATCH RFC 1/5] KVM: introduce a set_bit function for bitmaps in user space Takuya Yoshikawa
2010-04-11 17:08 ` Avi Kivity
2010-04-12 1:29 ` Takuya Yoshikawa
2010-04-12 9:12 ` Avi Kivity
2010-04-21 4:56 ` Fernando Luis Vázquez Cao
2010-04-21 8:09 ` Avi Kivity
2010-04-09 9:32 ` [PATCH RFC 2/5] KVM: use a rapper function to calculate the sizes of dirty bitmaps Takuya Yoshikawa
2010-04-11 17:12 ` Avi Kivity
2010-04-12 1:53 ` Takuya Yoshikawa
2010-04-09 9:34 ` [PATCH RFC 3/5] KVM: Use rapper functions to create and destroy " Takuya Yoshikawa
2010-04-11 17:13 ` Avi Kivity
2010-04-12 2:07 ` Takuya Yoshikawa
2010-04-12 9:13 ` Avi Kivity
2010-04-09 9:35 ` [PATCH RFC 4/5] KVM: add new members to the memory slot for double buffering of bitmaps Takuya Yoshikawa
2010-04-11 17:15 ` Avi Kivity
2010-04-12 2:15 ` Takuya Yoshikawa
2010-04-12 9:19 ` Avi Kivity
2010-04-12 9:30 ` Takuya Yoshikawa
2010-04-09 9:38 ` [PATCH RFC 5/5] KVM: This is the main part of the "moving dirty bitmaps to user space" Takuya Yoshikawa
2010-04-11 17:21 ` Avi Kivity
2010-04-12 2:29 ` Takuya Yoshikawa
2010-04-12 9:22 ` Avi Kivity
2010-04-12 20:55 ` Fernando Luis Vazquez Cao [this message]
2010-04-12 21:00 ` Avi Kivity
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