From owner-freebsd-net@freebsd.org Tue Nov 21 18:54:29 2017 Return-Path: Delivered-To: freebsd-net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id C5875DF6C33 for ; Tue, 21 Nov 2017 18:54:29 +0000 (UTC) (envelope-from rysto32@gmail.com) Received: from mail-qk0-x230.google.com (mail-qk0-x230.google.com [IPv6:2607:f8b0:400d:c09::230]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 7F1B37B9AE for ; Tue, 21 Nov 2017 18:54:29 +0000 (UTC) (envelope-from rysto32@gmail.com) Received: by mail-qk0-x230.google.com with SMTP id f63so13466179qke.8 for ; Tue, 21 Nov 2017 10:54:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=LlBgSYXeORlbvuBy76yVyfrWWY52GH2SBBjYANIid78=; b=q3wS7asksSybsY/t/Wr0RV5HoP2NwOfReWifTp1ZuNvtQTjmBfj/cQxucFWvMb53IE Q6W40aSX3y5/8/LL7MbeDAGFXiVRlR71zOqy2KiTH3Ob/oRMlB+qjhWNhEgAnGum3KyZ x2gzGbnsSR7L+GMBQHdrrMdVV7AeoMcM6tFOblF3/YzvB0o6oSm7cVhMidSYa3xd+jdy hOtUnskkksO3F0VmhhNH9QcTrZHYWCrqLsu+nasPX0aLBoMrGye+Fz6McLYDMm9WZXax p5+fL5hpObMcSyjxA+yn785vsp8NBR0Djc1LVVVV5jMK728Ygudgt9YUFPPS4bYSchpV EFrg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=LlBgSYXeORlbvuBy76yVyfrWWY52GH2SBBjYANIid78=; b=Oo7ubPW0KkweKECKWdvRiOtbPQ9tnwffn4sttKTp+9lnodxuC3JfOGwofk89BNIyoA bJK+GlPULU+YktdRwnlTy9KQM/7W6zuSkb/WaJTY9nt7pN87oToNBFeN0oQSBbhZirdn Lb/im6y5Y1Nqly2diA+bYYNMVytD22MvTRJEThvanxdmIli2PpwjZo48Kxup+u4UhAB/ oQ3yf5DN/ZkYWcLUzb3+DW6Hie0Pd0qHnH5kgHJFBAvqmjy4lBzObsjCUgzBHtVUftw6 6bq9s2eLQ4qWgu/mhHwnCN+APqyWKOY1pdZZaupVWyc3xZQtkZt2WaC3i8COfNjc6xcg rdgA== X-Gm-Message-State: AJaThX6s/cKgMEuQnviWKgp+Spwlo6QJy02m7qkgpDIv0NNrhgQ96Foi SGRKKMSMIrALwcT3ygJCK99Q4qE9O7gkLjMfbec= X-Google-Smtp-Source: AGs4zMb3O145mDOZv5LXi5li2N6qqFcmcpXynPbNMwejmSpuwbov+5idAzqu1vHVLEbbC72a4jSvrzVZFDt0awjTzC8= X-Received: by 10.55.221.212 with SMTP id u81mr28379124qku.174.1511290468623; Tue, 21 Nov 2017 10:54:28 -0800 (PST) MIME-Version: 1.0 Received: by 10.237.39.211 with HTTP; Tue, 21 Nov 2017 10:54:28 -0800 (PST) In-Reply-To: <65E7BF88-EBEA-47DA-806B-5BFD6783F2B4@sigsegv.be> References: <966f384c-10b4-d018-efb1-68a7064c9521@users.sourceforge.net> <65E7BF88-EBEA-47DA-806B-5BFD6783F2B4@sigsegv.be> From: Ryan Stone Date: Tue, 21 Nov 2017 13:54:28 -0500 Message-ID: Subject: Re: BPF packet pagesize limit To: Kristof Provost Cc: Catalin Salgau , freebsd-net Content-Type: text/plain; charset="UTF-8" X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Nov 2017 18:54:29 -0000 Do not allocate MJUM9BYTES clusters under any circumstances. Trying to allocate them when the system is under memory pressure is enormously expensive and stands a good chance of livelocking the system if you try to allocate too many too quickly, even when allocating with M_NOWAIT. Honestly, support for clusters > PAGE_SIZE should probably be retired from the kernel given the significant havoc they cause.