RE: [PATCH v3 3/5] treewide: use get_random_u32() when possible

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



From: Christophe Leroy
> Sent: 06 October 2022 18:43
...
> But taking into account that sp must remain 16 bytes aligned, would it
> be better to do something like ?
> 
> 	sp -= prandom_u32_max(PAGE_SIZE >> 4) << 4;

That makes me think...
If prandom_u32_max() is passed a (constant) power of 2 it doesn't
need to do the multiply, it can just do a shift right.

Doesn't it also always get a 32bit random value?
So actually get_random_u32() & PAGE_MASK & ~0xf is faster!

When PAGE_SIZE is 4k, PAGE_SIZE >> 4 is 256 so it could use:
	get_ramdom_u8() << 4

You also seem to have removed prandom_u32() in favour of
get_random_u32() but have added more prandom_xxxx() functions.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)




[Index of Archives]     [Kernel Development]     [DCCP]     [Linux ARM Development]     [Linux]     [Photo]     [Yosemite Help]     [Linux ARM Kernel]     [Linux SCSI]     [Linux x86_64]     [Linux Hams]

  Powered by Linux