From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4D24C7EE24 for ; Tue, 6 Jun 2023 14:26:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237565AbjFFO0B (ORCPT ); Tue, 6 Jun 2023 10:26:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59776 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234231AbjFFOZ5 (ORCPT ); Tue, 6 Jun 2023 10:25:57 -0400 Received: from mail-pl1-x633.google.com (mail-pl1-x633.google.com [IPv6:2607:f8b0:4864:20::633]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 187E8199D; Tue, 6 Jun 2023 07:25:25 -0700 (PDT) Received: by mail-pl1-x633.google.com with SMTP id d9443c01a7336-1b04949e5baso54248645ad.0; Tue, 06 Jun 2023 07:25:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1686061524; x=1688653524; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=/hmEz2MbCDzEXdAiTp6Aa2zyFmyqIvzUtehqc+a8JQM=; b=AgA8yJ2qSN0nKfzypklbbkOnFwubsWwLlNS1zuBDIfsGWUgRPxp4sXVz1ygkD7cM6T GcGX5fRp3+VQuDz3BG2Z8y3FcONjfMHDwCuxcO+jSaiOomqg5evWMmSjJcP/pA/N6yWY +iF9llU8Pu4KC8a/xjGJ7TsC0+wzeHpbwFjgHz2Rd38ed28bikd2JPt3KQE8LmWPb/7R xEY6cFSWXiYrvds/eg/8asRjB1q2dSwh4eupWCLOphNRJHKS5rJknVahnHLHZNQnQctd cxOzs0SkFVq7yEbHlsVMXSaYF+rU1vxQGuD04MkqqH1ZNTrERJtcPlLTonlhI/AKNzS/ c0sQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1686061524; x=1688653524; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=/hmEz2MbCDzEXdAiTp6Aa2zyFmyqIvzUtehqc+a8JQM=; b=c4Rs0+56tv4YIHuOsjq2+/Az/GjmB+k+xCH3Df8QDpN3qGg4gBeQkGltuSDcdmnzkW aou/u+PnjsE1PZXCHx8vAKJd5ywz4pAGjA+q/hS09MqGbUuXZDWEBiDbBSjblkIJly7n s7aToYggg4hmFcHP4X5DTJ3l/QcSPqTlV4Smzd5PeMT13b1XA7+xgE9tMmDsxDNKXi6Y dESmcsb8jFGXM7HNVMGs8WvoC8YO1Q/p3s+1BTY/quaRT8yf6/R/nb+O9t/fCa+1NT1x 2ESnfRTZLwpxhKIBsQvI7vLuqwq6Dl61+YjSoKvEcQQG/h0Wy46l4cC34zE/Zcf+UemU EBPQ== X-Gm-Message-State: AC+VfDzAOg+uFSFFMcffzDhHgS8e43cZHvr2oZpcLJT6Wkl/7ALrPZyu NSOBOBo4LnGmxN8bCbxRKmG3zvnrnIOct4Vrfyk= X-Google-Smtp-Source: ACHHUZ7d+2TaEqKX/qlkdetQq2bn1illhFx2x6aBzSwuTkXTmCZiL6B4FG2rL7icmDKgrCjNKyk9TlvUUPAvcq5qcdE= X-Received: by 2002:a17:902:e5cd:b0:1b2:28ca:d16 with SMTP id u13-20020a170902e5cd00b001b228ca0d16mr2457853plf.44.1686061524285; Tue, 06 Jun 2023 07:25:24 -0700 (PDT) MIME-Version: 1.0 References: <20230525125746.553874-1-aleksander.lobakin@intel.com> <20230525125746.553874-4-aleksander.lobakin@intel.com> <8828262f1c238ab28be9ec87a7701acd791af926.camel@gmail.com> <5aac6822-6fe5-e182-935e-7aa86f1e820d@intel.com> In-Reply-To: <5aac6822-6fe5-e182-935e-7aa86f1e820d@intel.com> From: Alexander Duyck Date: Tue, 6 Jun 2023 07:24:47 -0700 Message-ID: Subject: Re: [Intel-wired-lan] [PATCH net-next v2 03/12] iavf: optimize Rx buffer allocation a bunch To: Alexander Lobakin Cc: Paul Menzel , Jesper Dangaard Brouer , Larysa Zaremba , netdev@vger.kernel.org, Ilias Apalodimas , linux-kernel@vger.kernel.org, "David S. Miller" , Eric Dumazet , Michal Kubiak , intel-wired-lan@lists.osuosl.org, Jakub Kicinski , Paolo Abeni , Christoph Hellwig , Magnus Karlsson Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 6, 2023 at 5:49=E2=80=AFAM Alexander Lobakin wrote: > > From: Alexander Duyck > Date: Fri, 2 Jun 2023 10:50:02 -0700 > > Sorry for the silence, had sorta long weekend :p > > > On Fri, Jun 2, 2023 at 9:16=E2=80=AFAM Alexander Lobakin > > wrote: > [...] > > The other thing is you may want to double check CPU(s) you are > > expected to support as last I knew switch statements were still > > expensive due to all the old spectre/meltdown workarounds. > Wait, are switch-cases also affected? I wasn't aware of that. For sure I > didn't even consider using ops/indirect calls, but switch-cases... I saw > lots o'times people replacing indirections with switch-cases, what's the > point otherwise :D > > Thanks, > Olek I think it all depends on how the compiler implements them. I know switch cases used to be done as indirections in some cases. It is possible they did away with that in the compilers some time ago or came up with a fix to work around them. I just remember back when that came up people were going through and replacing switch cases with if/else blocks in the case of performance sensitive workloads. Odds are there have been workarounds added to address that, but it is just something to be aware of. 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dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20221208 header.b=AgA8yJ2q Subject: Re: [Intel-wired-lan] [PATCH net-next v2 03/12] iavf: optimize Rx buffer allocation a bunch X-BeenThere: intel-wired-lan@osuosl.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Wired Ethernet Linux Kernel Driver Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paul Menzel , Jesper Dangaard Brouer , Larysa Zaremba , netdev@vger.kernel.org, Ilias Apalodimas , linux-kernel@vger.kernel.org, Christoph Hellwig , Eric Dumazet , Michal Kubiak , intel-wired-lan@lists.osuosl.org, Jakub Kicinski , Paolo Abeni , "David S. Miller" , Magnus Karlsson Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: intel-wired-lan-bounces@osuosl.org Sender: "Intel-wired-lan" T24gVHVlLCBKdW4gNiwgMjAyMyBhdCA1OjQ54oCvQU0gQWxleGFuZGVyIExvYmFraW4KPGFsZWtz YW5kZXIubG9iYWtpbkBpbnRlbC5jb20+IHdyb3RlOgo+Cj4gRnJvbTogQWxleGFuZGVyIER1eWNr IDxhbGV4YW5kZXIuZHV5Y2tAZ21haWwuY29tPgo+IERhdGU6IEZyaSwgMiBKdW4gMjAyMyAxMDo1 MDowMiAtMDcwMAo+Cj4gU29ycnkgZm9yIHRoZSBzaWxlbmNlLCBoYWQgc29ydGEgbG9uZyB3ZWVr ZW5kIDpwCj4KPiA+IE9uIEZyaSwgSnVuIDIsIDIwMjMgYXQgOToxNuKAr0FNIEFsZXhhbmRlciBM b2Jha2luCj4gPiA8YWxla3NhbmRlci5sb2Jha2luQGludGVsLmNvbT4gd3JvdGU6Cj4KClsuLi5d Cgo+ID4gVGhlIG90aGVyIHRoaW5nIGlzIHlvdSBtYXkgd2FudCB0byBkb3VibGUgY2hlY2sgQ1BV KHMpIHlvdSBhcmUKPiA+IGV4cGVjdGVkIHRvIHN1cHBvcnQgYXMgbGFzdCBJIGtuZXcgc3dpdGNo IHN0YXRlbWVudHMgd2VyZSBzdGlsbAo+ID4gZXhwZW5zaXZlIGR1ZSB0byBhbGwgdGhlIG9sZCBz cGVjdHJlL21lbHRkb3duIHdvcmthcm91bmRzLgo+IFdhaXQsIGFyZSBzd2l0Y2gtY2FzZXMgYWxz byBhZmZlY3RlZD8gSSB3YXNuJ3QgYXdhcmUgb2YgdGhhdC4gRm9yIHN1cmUgSQo+IGRpZG4ndCBl dmVuIGNvbnNpZGVyIHVzaW5nIG9wcy9pbmRpcmVjdCBjYWxscywgYnV0IHN3aXRjaC1jYXNlcy4u LiBJIHNhdwo+IGxvdHMgbyd0aW1lcyBwZW9wbGUgcmVwbGFjaW5nIGluZGlyZWN0aW9ucyB3aXRo IHN3aXRjaC1jYXNlcywgd2hhdCdzIHRoZQo+IHBvaW50IG90aGVyd2lzZSA6RAo+Cj4gVGhhbmtz LAo+IE9sZWsKCkkgdGhpbmsgaXQgYWxsIGRlcGVuZHMgb24gaG93IHRoZSBjb21waWxlciBpbXBs ZW1lbnRzIHRoZW0uIEkga25vdwpzd2l0Y2ggY2FzZXMgdXNlZCB0byBiZSBkb25lIGFzIGluZGly ZWN0aW9ucyBpbiBzb21lIGNhc2VzLiBJdCBpcwpwb3NzaWJsZSB0aGV5IGRpZCBhd2F5IHdpdGgg dGhhdCBpbiB0aGUgY29tcGlsZXJzIHNvbWUgdGltZSBhZ28gb3IKY2FtZSB1cCB3aXRoIGEgZml4 IHRvIHdvcmsgYXJvdW5kIHRoZW0uIEkganVzdCByZW1lbWJlciBiYWNrIHdoZW4gdGhhdApjYW1l IHVwIHBlb3BsZSB3ZXJlIGdvaW5nIHRocm91Z2ggYW5kIHJlcGxhY2luZyBzd2l0Y2ggY2FzZXMg d2l0aAppZi9lbHNlIGJsb2NrcyBpbiB0aGUgY2FzZSBvZiBwZXJmb3JtYW5jZSBzZW5zaXRpdmUg d29ya2xvYWRzLiBPZGRzCmFyZSB0aGVyZSBoYXZlIGJlZW4gd29ya2Fyb3VuZHMgYWRkZWQgdG8g YWRkcmVzcyB0aGF0LCBidXQgaXQgaXMganVzdApzb21ldGhpbmcgdG8gYmUgYXdhcmUgb2YuCgpU aGFua3MsCgotIEFsZXgKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX18KSW50ZWwtd2lyZWQtbGFuIG1haWxpbmcgbGlzdApJbnRlbC13aXJlZC1sYW5Ab3N1b3Ns Lm9yZwpodHRwczovL2xpc3RzLm9zdW9zbC5vcmcvbWFpbG1hbi9saXN0aW5mby9pbnRlbC13aXJl ZC1sYW4K