From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon, 19 Aug 2013 22:51:41 GMT
Subject: Re: [PATCH v4] compat: Fix read() of 2GB and more on Mac OS X
Message-ID: <CA+55aFzAQjxB7HkDqR6_3wdex1t1Tbrf5CeUVyiVm=DRyDVhhQ@mail.gmail.com>
In-Reply-To: <7E527329-230E-4954-9942-8BB0935ACE4D@gmail.com>

On Mon, Aug 19, 2013 at 2:56 PM, Kyle J. McKay <mackyle@gmail.com> wrote:
>
> The fact that the entire file is read into memory when applying the filter
> does not seem like a good thing (see #7-#10 above).

Yeah, that's horrible. Its likely bad for performance too, because
even if you have enough memory, it blows everything out of the L2/L3
caches, and if you don't have enough memory it obviously causes other
problems.

So it would probably be a great idea to make the filtering code able
to do things in smaller chunks, but I suspect that the patch to chunk
up xread/xwrite is the right thing to do anyway.

              Linus