Subject: Re: RAW access to files
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: Wojciech Puchar <email@example.com>
Date: 12/14/2001 19:10:26
> As Thor (I think it was) pointed out, going out to disk - even if you
> hit the disk's cache - is significantly slower than finding the data
> already in host RAM.
so it will be little slower as ONE process.
but making lower load which is more important on multiuser system.
> > or/and large blocks it's no difference.
> I don't see what difference the block size makes. Could you explain?
when blocksize>>readahead size.
> >> (Unless the application provides such a place, which we agreed it
> >> shouldn't need to do.)
> > application can use O_ASYNC
> How does that help? To get readahead, there has to be somewhere to put
> the readahead. Direct I/O, by definition, doesn't keep kernel buffers,
you do this way: