Re: [PATCH 21/26] tty: Convert tty_struct bitfield to bools

[Peter Hurley]

On 09/03/2014 08:19 AM, One Thousand Gnomes wrote:
>> Ahh. Thanks for the insight, Alan.
>>
>> But set_bit() et. al. will generate an incredible amount of churn;
>> what if I split the fields up to prevent false-sharing?
> 
> Do you feel lucky ;-)

Hahaha  :)

> I'd rather set_bit and friends were used. They exist largely for this
> kind of reason and they also have atomic test/set methods which may in
> the longer term be very useful.
> 
> Yes it is churn can't argue with that.

Yuck. There should be a better way. IXANY mode is suddenly going to
have a ton of unnecessary bus locks on x86.

Note the ctrl_status field is a byte as well, which can't be RMW'ed by
the bit-locked primitives, and definitely should not be aggregated with
any adjacent field.

Regards,
Peter Hurley

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