From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amos Kong Subject: Re: [PATCH] crypto/xor.c: use 2 pages for xor speed testing Date: Tue, 17 Jun 2014 15:16:03 +0800 Message-ID: <20140617071603.GC8709@z.redhat.com> References: <1401930693-6549-1-git-send-email-akong@redhat.com> <201406052357.55383.marex@denx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-crypto@vger.kernel.org, herbert@gondor.apana.org.au, davem@davemloft.net To: Marek Vasut Return-path: Received: from mx1.redhat.com ([209.132.183.28]:44548 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755105AbaFQHQR (ORCPT ); Tue, 17 Jun 2014 03:16:17 -0400 Content-Disposition: inline In-Reply-To: <201406052357.55383.marex@denx.de> Sender: linux-crypto-owner@vger.kernel.org List-ID: On Thu, Jun 05, 2014 at 11:57:55PM +0200, Marek Vasut wrote: > On Thursday, June 05, 2014 at 03:11:33 AM, Amos Kong wrote: > > In crypto/xor.c: calibrate_xor_blocks(), we allocated total 4 pages to > > do xor speed testing, the BENCH_SIZE is 1 page, and we skipped 2 pages > > when we set b2. > > > > It seems that total 2 pages are enough without skipping 2 pages. > > > > Signed-off-by: Amos Kong > > --- > > crypto/xor.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/crypto/xor.c b/crypto/xor.c > > index 35d6b3a..609dfb5 100644 > > --- a/crypto/xor.c > > +++ b/crypto/xor.c > > @@ -114,12 +114,12 @@ calibrate_xor_blocks(void) > > * test the XOR speed, we don't really want kmemcheck to warn about > > * reading uninitialized bytes here. > > */ > > - b1 = (void *) __get_free_pages(GFP_KERNEL | __GFP_NOTRACK, 2); > > + b1 = (void *) __get_free_pages(GFP_KERNEL | __GFP_NOTRACK, 1); > > if (!b1) { > > printk(KERN_WARNING "xor: Yikes! No memory available.\n"); > > return -ENOMEM; > > } > > - b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE; > > + b2 = b1 + BENCH_SIZE; > > > > /* > > * If this arch/cpu has a short-circuited selection, don't loop through > > @@ -154,7 +154,7 @@ calibrate_xor_blocks(void) > > #undef xor_speed > > > > out: > > - free_pages((unsigned long)b1, 2); > > + free_pages((unsigned long)b1, 1); > > > > active_template = fastest; > > return 0; > > I think this does make sense, but I am not 100% sure, sorry. > > ... > > While looking at this code, can anyone explain to me why we have this stuff in > crypto/xor.c please ? > > 135 #define xor_speed(templ) do_xor_speed((templ), b1, b2) > 136 > 137 if (fastest) { > 138 printk(KERN_INFO "xor: automatically using best " > 139 "checksumming function:\n"); > 140 xor_speed(fastest); > 141 goto out; > 142 } else { > [...] > 149 } > 150 > 151 printk(KERN_INFO "xor: using function: %s (%d.%03d MB/sec)\n", > 152 fastest->name, fastest->speed / 1000, fastest->speed % 1000); > 153 > 154 #undef xor_speed > > Why do we not call do_xor_speed(fastest, b1, b2); right away , but we #define > xor_speed() instead ? This looks like some remnant or nonsense to me. Shall I > remove that with a patch ? You are right. > Best regards, > Marek Vasut -- Amos.