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 3D16EC77B6F for ; Thu, 13 Apr 2023 20:49:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230020AbjDMUtz (ORCPT ); Thu, 13 Apr 2023 16:49:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39276 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230036AbjDMUtx (ORCPT ); Thu, 13 Apr 2023 16:49:53 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7724B902D for ; Thu, 13 Apr 2023 13:49:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681418950; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=iLaM67UvMzd8NeAnSp7Vx35R3ooH8nXVeMsYhQtDrpw=; b=MhZsc1+KiHrRLS6AXsfIkk1twpz5pTRaD4Gnv5duQwSih1KZtFzt0YLSg9AESsFy6RIILZ qDHaJsJQVTj6t2xjcftj7QdONG240XARVQfM/g3PsY64PGdnUvsjFjKlrIvP74WabQGVmN Sxo65cMtpmSaB70k2gxXG6BPnYEO+2g= Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-389-2qe-DqlKMFq-k_FeYxH26g-1; Thu, 13 Apr 2023 16:49:07 -0400 X-MC-Unique: 2qe-DqlKMFq-k_FeYxH26g-1 Received: by mail-ed1-f69.google.com with SMTP id a5-20020a509e85000000b0050504899d78so3371700edf.16 for ; Thu, 13 Apr 2023 13:49:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681418946; x=1684010946; h=mime-version:message-id:date:references:in-reply-to:subject:cc:to :from:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=iLaM67UvMzd8NeAnSp7Vx35R3ooH8nXVeMsYhQtDrpw=; b=bTA+S3FG99N7roc0g1P95EbGJfZwB25Pd43F9C5qPnP0bKgcwBWKNzzFhuGDYNuB2T XkSe+JrXIiPbnotgzMR28p8ImBfXByXq8zmtl8Ceea1mUVMcIS7W9Julzhj8qrj0I8gN ezfxKv7LN4b0/vsaCw0BecnmaQl94dKBh9v2TKHqJgvqpi683Wu4LffsotSfEu1nKuWZ 4SKCxo9bNKfb4enT7a82KMaDMhX74hS8chf0tcMGvSlQ2l73gaHWgptCFWlH4hVBbPH8 ovGjhqJnkb2WktkId3oGD1jLT6RzBte3c0rM0j6HlUBzahOUStK/EZlOSgOkxr/8Wmmu tfGw== X-Gm-Message-State: AAQBX9ea5ght2vPiOiagCdkGQxub5+J7FUvy0wyVLU17omMMhyLWio5G 7Yk5acMOS+FNRuzuW26fpwA4+zXBMbO25gTi5Lo6kq6lOrABEo4dohZ3rYUH+1Z3ibmFgfI1vMp FFIwT4xXVSqT+ X-Received: by 2002:a17:907:984c:b0:948:b988:8cc3 with SMTP id jj12-20020a170907984c00b00948b9888cc3mr4147785ejc.75.1681418945776; Thu, 13 Apr 2023 13:49:05 -0700 (PDT) X-Google-Smtp-Source: AKy350bPGSR3gQ4upooNybI4H3M/HmIOXfKfoJqvk974LBdVJoWBT91lmcIroESBjv99VoMziDvCCg== X-Received: by 2002:a17:907:984c:b0:948:b988:8cc3 with SMTP id jj12-20020a170907984c00b00948b9888cc3mr4147755ejc.75.1681418945065; Thu, 13 Apr 2023 13:49:05 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id f21-20020a05640214d500b0050489201b81sm1255849edx.26.2023.04.13.13.49.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Apr 2023 13:49:04 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id E9ECEAA7BA3; Thu, 13 Apr 2023 22:49:03 +0200 (CEST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Kal Cutter Conley Cc: Maciej Fijalkowski , =?utf-8?B?QmrDtnJu?= =?utf-8?B?IFTDtnBlbA==?= , Magnus Karlsson , Jonathan Lemon , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jonathan Corbet , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH bpf-next v3 1/3] xsk: Support UMEM chunk_size > PAGE_SIZE In-Reply-To: References: <20230406130205.49996-1-kal.conley@dectris.com> <20230406130205.49996-2-kal.conley@dectris.com> <87sfdckgaa.fsf@toke.dk> <875ya12phx.fsf@toke.dk> <87ile011kz.fsf@toke.dk> X-Clacks-Overhead: GNU Terry Pratchett Date: Thu, 13 Apr 2023 22:49:03 +0200 Message-ID: <87o7nrzeww.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Kal Cutter Conley writes: >> Well, you mentioned yourself that: >> >> > The disadvantage of this patchset is requiring the user to allocate >> > HugeTLB pages which is an extra complication. > > It's a small extra complication *for the user*. However, users that > need this feature are willing to allocate hugepages. We are one such > user. For us, having to deal with packets split into disjoint buffers > (from the XDP multi-buffer paradigm) is a significantly more annoying > complication than allocating hugepages (particularly on the RX side). "More annoying" is not a great argument, though. You're basically saying "please complicate your code so I don't have to complicate mine". And since kernel API is essentially frozen forever, adding more of them carries a pretty high cost, which is why kernel developers tend not to be easily swayed by convenience arguments (if all you want is a more convenient API, just build one on top of the kernel primitives and wrap it into a library). So you'll need to come up with either (1) a use case that you *can't* solve without this new API (with specifics as to why that is the case), or (2) a compelling performance benchmark showing the complexity is worth it. Magnus indicated he would be able to produce the latter, in which case I'm happy to be persuaded by the numbers. In any case, however, the behaviour needs to be consistent wrt the rest of XDP, so it's not as simple as just increasing the limit (as I mentioned in my previous email). -Toke