From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by passt.top (Postfix) with ESMTP id A084E5A0265 for ; Tue, 18 Oct 2022 10:40:05 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1666082404; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=a8+htJ/Exq+aSJ8SEzPVgW4Jb5jXPhx/LN1JVXe5pw4=; b=JskTSZklwkEn0Fu7OJdpZXbjHWxeaReH0oNqLJ91jHQPu6xcbytEXKZoSkccuWC8YjSKmW sGFtqdtHnAVlaUvjBX+VWCzDX3v6LWjx4SQvLhCamNguowjPiqK9IV+1rI5PjxDdnmZS2h dModaD+hxCmzE8busQrWfeXBmNaDrdI= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-325-kBbDkHZJPWGJ1xVdNgxPpg-1; Tue, 18 Oct 2022 04:40:01 -0400 X-MC-Unique: kBbDkHZJPWGJ1xVdNgxPpg-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id BE6EA3C0CD50; Tue, 18 Oct 2022 08:40:00 +0000 (UTC) Received: from maya.cloud.tilaa.com (ovpn-208-31.brq.redhat.com [10.40.208.31]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7252A409AE1; Tue, 18 Oct 2022 08:40:00 +0000 (UTC) Date: Tue, 18 Oct 2022 05:05:13 +0200 From: Stefano Brivio To: David Gibson Subject: Re: [PATCH 08/14] tap: Remove unhelpeful vnet_pre optimization from tap_send() Message-ID: <20221018050513.04fae95b@elisabeth> In-Reply-To: <20221017085807.473470-9-david@gibson.dropbear.id.au> References: <20221017085807.473470-1-david@gibson.dropbear.id.au> <20221017085807.473470-9-david@gibson.dropbear.id.au> Organization: Red Hat MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-ID-Hash: XSNLM446CK7N7WGECVDFLRQYHCRAGCWG X-Message-ID-Hash: XSNLM446CK7N7WGECVDFLRQYHCRAGCWG X-MailFrom: sbrivio@redhat.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: passt-dev@passt.top X-Mailman-Version: 3.3.3 Precedence: list List-Id: Development discussion and patches for passt Archived-At: <> Archived-At: List-Archive: <> List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Mon, 17 Oct 2022 19:58:01 +1100 David Gibson wrote: > Callers of tap_send() can optionally use a small optimization by adding > extra space for the 4 byte length header used on the qemu socket interface. > tap_ip_send() is currently the only user of this, but this is used only > for "slow path" ICMP and DHCP packets, so there's not a lot of value to > the optimization. Not anymore, definitely. It used to look quite bad in perf(1) when I shuffled connection data around. -- Stefano