On May 9 2007 15:38, Jens Axboe wrote:
>> I am a mdadm/disk/hard drive fanatic, I was curious:
>>
>> >On i386, we can at most fit 256 scatterlist elements into a page,
>> >and on x86-64 we are stuck with 128. So that puts us somewhere
>> >between 512kb and 1024kb for a single IO.
>>
>> How come 32bit is 256 and 64 is only 128?
>>
>> I am sure it is something very fundamental/simple but I was curious, I
>> would think x86_64 would fit/support more scatterlists in a page.
>
>Because of the size of the scatterlist structure. As pointers are bigger
>on 64-bit archs, the scatterlist structure ends up being bigger. The
>page size on x86-64 is 4kb, hence the number of structures you can fit
>in a page is smaller.
I take it this problem "goes away" on arches with 8KB page_size?
Jan
--
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
