svn commit: r274017 - head/sys/kern

[Hans Petter Selasky]

On 11/03/14 09:23, Julian Elischer wrote:
> On 11/3/14, 4:21 PM, Julian Elischer wrote:
>> On 11/3/14, 3:46 PM, Mateusz Guzik wrote:
>>> Author: mjg
>>> Date: Mon Nov  3 07:46:51 2014
>>> New Revision: 274017
>>> URL: https://svnweb.freebsd.org/changeset/base/274017
>>>
>>> Log:
>>>    Provide an on-stack temporary buffer for small ioctl requests.
>> I'm not sure I like this. We don't know how many more levels
>> of stack may be needed.
>> I know that machines are getting faster with more memory,
>> but the current move towards bloating out the
> ... "bloating out the stack" ...
>> worries me.  we started out with a single page of stack (SHARED
>> with the U-area!). I think we are now at several pages.. I forget, is
>> it 8?
>> I'm open to being persuaded but I think we need to have a discussion
>> about stack usage. We used to say that anything greater that, say
>> 64 bytes should probably be allocated.
>>

Hi,

I think this patch can give a benefit for the USB stack and CUSE4BSD, 
because it does frequent IOCTLs. Regarding the stack usage, maybe this 
general purpose optimisation can be allocated from the thread structure?

--HPS