On Wed, 16 Mar 2011, George Spelvin wrote: > > Where's your signed-off-by? > > Somewhere under the pile of crap on my desk. :-) > (More to the point, waiting for me to think it's good enough to submit > For Real.) > Patches that you would like to propose but don't think are ready for merge should have s/PATCH/RFC/ done on the subject line. > > Nice cleanup. > > > > "flag" should be unsigned long in all of these functions: the constants > > are declared with UL suffixes in slab.h. > > Actually, I did that deliberately. Because there's a problem I keep > wondering about, which repeats many many times in the kernel: > You deliberately created a helper function to take an unsigned int when the actuals being passed in are all unsigned long to trigger a discussion on why they are unsigned long? > *Why* are they unsigned long? That's an awkward type: 32 bits on many > architectures, so we can't portably assign more than 32 bits, and on > platforms where it's 64 bits, the upper 32 are just wasting space. > (And REX prefixes on x86-64.) > unsigned long uses the native word size of the architecture which can generate more efficient code; we typically imply that flags have a limited size by including leading zeros in their definition for 32-bit compatibility: #define SLAB_DEBUG_FREE 0x00000100UL /* DEBUG: Perform (expensive) checks on free */ #define SLAB_RED_ZONE 0x00000400UL /* DEBUG: Red zone objs in a cache */ #define SLAB_POISON 0x00000800UL /* DEBUG: Poison objects */ ... -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>