lkml.org 
[lkml]   [2014]   [Jan]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 5/5] lockdep: pack subclass/trylock/read/check into a single argument
    On Tue, 21 Jan 2014 19:43:10 +0100
    Oleg Nesterov <oleg@redhat.com> wrote:

    > On 01/21, Dave Jones wrote:
    > >
    > > On Tue, Jan 21, 2014 at 03:10:22PM +0100, Peter Zijlstra wrote:
    > > >
    > > > I tried the below but filed to see my vmlinux shrink, maybe I'm just not
    > > > building the right kernel, or otherwise GCC is stupid.
    > > >
    > > > -extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
    > > > - int trylock, int read, int check,
    > > > - struct lockdep_map *nest_lock, unsigned long ip);
    > > > +struct lockdep_acquire_flags {
    > > > + unsigned long subclass : 3;
    > > > + unsigned long trylock : 1;
    > > > + unsigned long read : 2;
    > > > + unsigned long check : 1;
    > > > +};
    > >
    > > As it's only 7 bits here, could we pack them into a char ?
    >
    > Do you mean __attribute__((packed)) ?
    >

    I think Dave means:

    unsigned char subclass : 3;
    unsigned char trylock : 1;
    unsigned char read : 2;
    unsigned char check : 1;

    -- Steve


    \
     
     \ /
      Last update: 2014-01-21 20:21    [W:2.716 / U:0.112 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site