Re: [PATCH v10 05/14] unwind_user/deferred: Add unwind cache

[Steven Rostedt]

On June 19, 2025 5:04:36 AM EDT, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>On Thu, Jun 19, 2025 at 04:47:14AM -0400, Steven Rostedt wrote:
>> On Thu, 19 Jun 2025 09:56:11 +0200
>> Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>> 
>> > Well, the trivial solution is to make it 511 and call it a day. Don't
>> > make things complicated if you don't have to.
>> 
>> I don't know if this is more complicated, but it should make it fit
>> nicely in a page:
>> 
>>   /* Make the cache fit in a page */
>>   #define UNWIND_MAX_ENTRIES                                      \
>>         ((PAGE_SIZE - sizeof(struct unwind_cache)) / sizeof(long))
>
>Right, that's the fancy way of spelling 511 :-) Except on 32bit, where
>it now spells 1023 instead.
>
>Did you want that bitness difference?
>
>Also, you ready for some *reaaally* big numbers on Power/ARM with 64K
>pages? :-)

Bah, yeah, I need to use a size and not just PAGE_SIZE.

 Thanks,

-- Steve