Hi Jerry,

I am not sure if you have tried the below algorithm successfully with O_DIRECT. But what 
O_DIRECT needs is "Soft-block aligned" buffer on not Byte-aligned.

In the alternative you have mentioned, I understand that it is without 
O_DIRECT. If that's the case, I will try it out for sure, also with higher 
chunk-sizes.

Regards,
Gopal Sukumar.

Jerry Johns wrote:
if you're trying to align malloc'ed memory to an x-byte boundary, you can try 
to do this:
e.g, aligning to a 2-byte boundary,

unaligned_addr = malloc(size + 0x3);
aligned_addr = ((unaligned_addr+0x3) & (~0x3));

This should allow you to request the maximum possible size, and then allow you 
to increment your unaligned address up to its proper alignment (all within your 
malloc'ed space)
You'd still try to free from the unaligned addr though;

As for alternative methods to speeding up your filesystem writes, I've done 
some testing on write speeds, and noticed that writing in higher volume chunks 
significantly boosted by speeds
I usually write in 8K chunks, but you should experiement with other sizes as 
well.

Thanks,

Jerry Johns
Design Engineer
Nuvation Research Corp - Canada
Tel: (519) 746-2304 ext. 221
www.nuvation.com<http://www.nuvation.com>





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