lkml.org 
[lkml]   [2010]   [Aug]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH v8 00/16] Provide a zero-copy method on KVM virtio-net.
  On 07/30/2010 06:46 PM, Shirley Ma wrote:
> Hello Avi,
>
> On Fri, 2010-07-30 at 08:02 +0300, Avi Kivity wrote:
>> get_user_pages() is indeed slow. But what about
>> get_user_pages_fast()?
>>
>> Note that when the page is first touched, get_user_pages_fast() falls
>> back to get_user_pages(), so the latency needs to be measured after
>> quite a bit of warm-up.
> Yes, I used get_user_pages_fast, however if falled back to
> get_user_pages() when the apps doesn't allocate buffer on the same page.
> If I run a single ping, the RTT is extremely high, but when running
> multiple pings, the RTT time reduce significantly, but still it is not
> as fast as copy from my initial test. I am thinking that we might need
> to pre-pin memory pool.
>

I don't understand. Under what conditions do you use get_user_pages()
instead of get_user_pages_fast()? Why?

--
error compiling committee.c: too many arguments to function



\
 
 \ /
  Last update: 2010-08-01 10:21    [W:0.084 / U:0.220 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site