[lkml]   [2018]   [Jun]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 1/2] locking: Implement an algorithm choice for Wound-Wait mutexes
On Wed, Jun 13, 2018 at 09:47:44AM +0200, Thomas Hellstrom wrote:
> -----
> +The algorithm (Wait-Die vs Wound-Wait) is chosen using the _is_wait_die
> +argument to DEFINE_WW_CLASS(). As a rough rule of thumb, use Wound-Wait iff you
> +typically expect the number of simultaneous competing transactions to be small,
> +and the rollback cost can be substantial.
> +
> Three different ways to acquire locks within the same w/w class. Common
> definitions for methods #1 and #2:
> -static DEFINE_WW_CLASS(ww_class);
> +static DEFINE_WW_CLASS(ww_class, false);

Minor nit on the api here. Having a "flag" is a royal pain. You have
to go and look up exactly what that "true/false" means every time you
run across it in code to figure out what it means. Don't do that if at
all possible.

Make a new api:
instead that then wraps that boolean internally to switch between the
different types. That way the api is "self-documenting" and we all know
what is going on without having to dig through a header file.


greg k-h

 \ /
  Last update: 2018-06-13 09:55    [W:0.073 / U:1.512 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site