Re: [patch 1/3] add the fsblock layer

[Nick Piggin <nickpiggin@yahoo.com.au>]

Andi Kleen wrote:
> Nick Piggin <npiggin@suse.de> writes:
> 
> 
> [haven't read everything, just commenting on something that caught my eye]
> 
> 
>>+struct fsblock {
>>+	atomic_t	count;
>>+	union {
>>+		struct {
>>+			unsigned long	flags; /* XXX: flags could be int for better packing */
> 
> 
> int is not supported by many architectures, but works on x86 at least.

Yeah, that would be nice. We could actually use this for buffer_head as well,
but saving 4% there isn't so important as saving 20% for fsblock :)


> Hmm, could define a macro DECLARE_ATOMIC_BITMAP(maxbit) that expands to the smallest
> possible type for each architecture. And a couple of ugly casts for set_bit et.al.
> but those could be also hidden in macros. Should be relatively easy to do.

Cool. It would probably be useful for other things as well.

-- 
SUSE Labs, Novell Inc.