From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Marvin Date: Mon, 15 Mar 2004 12:40:07 +0000 Subject: Re: [PATCH] Revised fix for show_mem panic Message-Id: <200403151240.i2FCe7M19805@udlkern.fc.hp.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Oops. Usually I forget to include the patch. This time I sent the patch without the intro text: > Would it make sense to do only the first __get_user() _unless_ the > "struct page" crosses a page? Most likely. Although code that calls ia64_pfn_valid is going to be dereferencing the page structure anyway, a page structure will always cross a 1st level cache line, and will often cross a second level cache line. The code may or may not touch both parts of the the structure, so the test may prevent an unecessary cache line load, and it won't take that many cycles to test for the case. John