From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <48AD69EA.9090202@linux-foundation.org> Date: Thu, 21 Aug 2008 08:13:14 -0500 From: Christoph Lameter MIME-Version: 1.0 Subject: Re: [patch] mm: rewrite vmap layer References: <20080818133224.GA5258@wotan.suse.de> <48AADBDC.2000608@linux-foundation.org> <20080820090234.GA7018@wotan.suse.de> <48AC244F.1030104@linux-foundation.org> <87y72q3kem.fsf@skyscraper.fehenstaub.lan> In-Reply-To: <87y72q3kem.fsf@skyscraper.fehenstaub.lan> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Johannes Weiner Cc: Nick Piggin , Andrew Morton , Linux Memory Management List , linux-arch@vger.kernel.org List-ID: Johannes Weiner wrote: > I have not much clue about the users but shouldn't you use vmalloc > anyway if you don't need physically contiguous pages? physical memory has the advantage that it does not need a page table and its therefore more efficient to access. Plus the overhead of having to maintain a mapping is gone. Memory is suitable for I/O without scatter gather etc etc. > So while it would be usable then to have both vmap and vunmap work in > atomic context, I don't really get the fallback use case..? Classic example: A network driver wants contiguous memory for a jumbo frame. Fallback to scatter gather is possible but not as effective. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org