From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.huckk@gmail.com (Will Huck) Date: Wed, 20 Feb 2013 08:43:30 +0800 Subject: Should a swapped out page be deleted from swap cache? In-Reply-To: References: <5122C9B3.10306@gmail.com> Message-ID: <51241C32.3050500@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 02/20/2013 03:06 AM, Hugh Dickins wrote: > On Tue, 19 Feb 2013, Will Huck wrote: >> Another question: > I don't see the connection to deleting a swapped out page from swap cache. > >> Why kernel memory mapping use direct mapping instead of kmalloc/vmalloc which >> will setup mapping on demand? > I may misunderstand you, and "kernel memory mapping". > > kmalloc does not set up a mapping, it uses the direct mapping already set up. > > It would be circular if the basic page allocation primitives used kmalloc, > since kmalloc relies on the basic page allocation primitives. > > vmalloc is less efficient than using the direct mapping (repeated setup > and teardown, no use of hugepages), but necessary when you want a larger Is there tlb flush in setup and teardown process? and they also expensive? > virtual array than you're likely to find from the buddy allocator. > > Hugh