From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from perceval.ideasonboard.com ([213.167.242.64]:44572 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1032525AbeEXKrf (ORCPT ); Thu, 24 May 2018 06:47:35 -0400 From: Laurent Pinchart To: Kieran Bingham Cc: linux-renesas-soc@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH v4 02/11] media: vsp1: Remove packed attributes from aligned structures Date: Thu, 24 May 2018 13:47:30 +0300 Message-ID: <1879534.EAt6bC61BJ@avalon> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-renesas-soc-owner@vger.kernel.org List-ID: Hi Kieran, Thank you for the patch. On Thursday, 3 May 2018 16:36:13 EEST Kieran Bingham wrote: > The use of the packed attribute can cause a performance penalty for > all accesses to the struct members, as the compiler will assume that the > structure has the potential to have an unaligned base. > > These structures are all correctly aligned and contain no holes, thus > the attribute is redundant and negatively impacts performance, so we > remove the attributes entirely. With gcc 6.4.0 this patch makes no difference on the generated object. Is it worth it ? > Signed-off-by: Kieran Bingham You forget to pick Geert's review tag. > --- > v2 > - Remove attributes entirely > --- > drivers/media/platform/vsp1/vsp1_dl.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/platform/vsp1/vsp1_dl.c > b/drivers/media/platform/vsp1/vsp1_dl.c index c7fa1cb088cd..f4cede9b9b43 > 100644 > --- a/drivers/media/platform/vsp1/vsp1_dl.c > +++ b/drivers/media/platform/vsp1/vsp1_dl.c > @@ -25,19 +25,19 @@ > struct vsp1_dl_header_list { > u32 num_bytes; > u32 addr; > -} __attribute__((__packed__)); > +}; > > struct vsp1_dl_header { > u32 num_lists; > struct vsp1_dl_header_list lists[8]; > u32 next_header; > u32 flags; > -} __attribute__((__packed__)); > +}; > > struct vsp1_dl_entry { > u32 addr; > u32 data; > -} __attribute__((__packed__)); > +}; > > /** > * struct vsp1_dl_body - Display list body -- Regards, Laurent Pinchart From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [PATCH v4 02/11] media: vsp1: Remove packed attributes from aligned structures Date: Thu, 24 May 2018 13:47:30 +0300 Message-ID: <1879534.EAt6bC61BJ@avalon> References: Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by gabe.freedesktop.org (Postfix) with ESMTPS id C559C6E01C for ; Thu, 24 May 2018 10:47:35 +0000 (UTC) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Kieran Bingham Cc: linux-renesas-soc@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org List-Id: dri-devel@lists.freedesktop.org SGkgS2llcmFuLAoKVGhhbmsgeW91IGZvciB0aGUgcGF0Y2guCgpPbiBUaHVyc2RheSwgMyBNYXkg MjAxOCAxNjozNjoxMyBFRVNUIEtpZXJhbiBCaW5naGFtIHdyb3RlOgo+IFRoZSB1c2Ugb2YgdGhl IHBhY2tlZCBhdHRyaWJ1dGUgY2FuIGNhdXNlIGEgcGVyZm9ybWFuY2UgcGVuYWx0eSBmb3IKPiBh bGwgYWNjZXNzZXMgdG8gdGhlIHN0cnVjdCBtZW1iZXJzLCBhcyB0aGUgY29tcGlsZXIgd2lsbCBh c3N1bWUgdGhhdCB0aGUKPiBzdHJ1Y3R1cmUgaGFzIHRoZSBwb3RlbnRpYWwgdG8gaGF2ZSBhbiB1 bmFsaWduZWQgYmFzZS4KPiAKPiBUaGVzZSBzdHJ1Y3R1cmVzIGFyZSBhbGwgY29ycmVjdGx5IGFs aWduZWQgYW5kIGNvbnRhaW4gbm8gaG9sZXMsIHRodXMKPiB0aGUgYXR0cmlidXRlIGlzIHJlZHVu ZGFudCBhbmQgbmVnYXRpdmVseSBpbXBhY3RzIHBlcmZvcm1hbmNlLCBzbyB3ZQo+IHJlbW92ZSB0 aGUgYXR0cmlidXRlcyBlbnRpcmVseS4KCldpdGggZ2NjIDYuNC4wIHRoaXMgcGF0Y2ggbWFrZXMg bm8gZGlmZmVyZW5jZSBvbiB0aGUgZ2VuZXJhdGVkIG9iamVjdC4gSXMgaXQgCndvcnRoIGl0ID8K Cj4gU2lnbmVkLW9mZi1ieTogS2llcmFuIEJpbmdoYW0gPGtpZXJhbi5iaW5naGFtK3JlbmVzYXNA aWRlYXNvbmJvYXJkLmNvbT4KCllvdSBmb3JnZXQgdG8gcGljayBHZWVydCdzIHJldmlldyB0YWcu Cgo+IC0tLQo+IHYyCj4gIC0gUmVtb3ZlIGF0dHJpYnV0ZXMgZW50aXJlbHkKPiAtLS0KPiAgZHJp dmVycy9tZWRpYS9wbGF0Zm9ybS92c3AxL3ZzcDFfZGwuYyB8IDYgKysrLS0tCj4gIDEgZmlsZSBj aGFuZ2VkLCAzIGluc2VydGlvbnMoKyksIDMgZGVsZXRpb25zKC0pCj4gCj4gZGlmZiAtLWdpdCBh L2RyaXZlcnMvbWVkaWEvcGxhdGZvcm0vdnNwMS92c3AxX2RsLmMKPiBiL2RyaXZlcnMvbWVkaWEv cGxhdGZvcm0vdnNwMS92c3AxX2RsLmMgaW5kZXggYzdmYTFjYjA4OGNkLi5mNGNlZGU5YjliNDMK PiAxMDA2NDQKPiAtLS0gYS9kcml2ZXJzL21lZGlhL3BsYXRmb3JtL3ZzcDEvdnNwMV9kbC5jCj4g KysrIGIvZHJpdmVycy9tZWRpYS9wbGF0Zm9ybS92c3AxL3ZzcDFfZGwuYwo+IEBAIC0yNSwxOSAr MjUsMTkgQEAKPiAgc3RydWN0IHZzcDFfZGxfaGVhZGVyX2xpc3Qgewo+ICAJdTMyIG51bV9ieXRl czsKPiAgCXUzMiBhZGRyOwo+IC19IF9fYXR0cmlidXRlX18oKF9fcGFja2VkX18pKTsKPiArfTsK PiAKPiAgc3RydWN0IHZzcDFfZGxfaGVhZGVyIHsKPiAgCXUzMiBudW1fbGlzdHM7Cj4gIAlzdHJ1 Y3QgdnNwMV9kbF9oZWFkZXJfbGlzdCBsaXN0c1s4XTsKPiAgCXUzMiBuZXh0X2hlYWRlcjsKPiAg CXUzMiBmbGFnczsKPiAtfSBfX2F0dHJpYnV0ZV9fKChfX3BhY2tlZF9fKSk7Cj4gK307Cj4gCj4g IHN0cnVjdCB2c3AxX2RsX2VudHJ5IHsKPiAgCXUzMiBhZGRyOwo+ICAJdTMyIGRhdGE7Cj4gLX0g X19hdHRyaWJ1dGVfXygoX19wYWNrZWRfXykpOwo+ICt9Owo+IAo+ICAvKioKPiAgICogc3RydWN0 IHZzcDFfZGxfYm9keSAtIERpc3BsYXkgbGlzdCBib2R5CgotLSAKUmVnYXJkcywKCkxhdXJlbnQg UGluY2hhcnQKCgoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X18KZHJpLWRldmVsIG1haWxpbmcgbGlzdApkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3Jn Cmh0dHBzOi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vZHJpLWRldmVs Cg==