From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from toip4.srvr.bell.ca ([209.226.175.87]) by tomts10-srv.bellnexxia.net (InterMail vM.5.01.06.13 201-253-122-130-113-20050324) with ESMTP id <20071116144744.FYEY1733.tomts10-srv.bellnexxia.net@toip4.srvr.bell.ca> for ; Fri, 16 Nov 2007 09:47:44 -0500 Date: Fri, 16 Nov 2007 09:47:43 -0500 From: Mathieu Desnoyers Subject: Re: [RFC 5/7] LTTng instrumentation mm Message-ID: <20071116144742.GA17255@Krystal> References: <20071113193349.214098508@polymtl.ca> <20071113194025.150641834@polymtl.ca> <1195160783.7078.203.camel@localhost> <20071115215142.GA7825@Krystal> <1195164977.27759.10.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <1195164977.27759.10.camel@localhost> Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Hansen Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mbligh@google.com List-ID: * Dave Hansen (haveblue@us.ibm.com) wrote: > On Thu, 2007-11-15 at 16:51 -0500, Mathieu Desnoyers wrote: > > * Dave Hansen (haveblue@us.ibm.com) wrote: > > > > On Tue, 2007-11-13 at 14:33 -0500, Mathieu Desnoyers wrote: > > > > linux-2.6-lttng/mm/page_io.c 2007-11-13 09:49:35.000000000 -0500 > > > > @@ -114,6 +114,7 @@ int swap_writepage(struct page *page, st > > > > rw |= (1 << BIO_RW_SYNC); > > > > count_vm_event(PSWPOUT); > > > > set_page_writeback(page); > > > > + trace_mark(mm_swap_out, "address %p", page_address(page)); > > > > unlock_page(page); > > > > submit_bio(rw, bio); > > > > out: > > > > > > I'm not sure all this page_address() stuff makes any sense on highmem > > > systems. How about page_to_pfn()? > > > > Knowing which page frame number has been swapped out is not always as > > relevant as knowing the page's virtual address (when it has one). Saving > > both the PFN and the page's virtual address could give us useful > > information when the page is not mapped. > > For most (all?) architectures, the PFN and the virtual address in the > kernel's linear are interchangeable with pretty trivial arithmetic. All > pages have a pfn, but not all have a virtual address. Thus, I suggested > using the pfn. What kind of virtual addresses are you talking about? > Hrm, in asm-generic/memory_model.h, we have various versions of __page_to_pfn. Normally they all cast the result to (unsigned long), except for : #elif defined(CONFIG_SPARSEMEM_VMEMMAP) /* memmap is virtually contigious. */ #define __pfn_to_page(pfn) (vmemmap + (pfn)) #define __page_to_pfn(page) ((page) - vmemmap) So I guess the result is a pointer ? Should this be expected ? Mathieu -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- 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