From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3C6E6245019 for ; Fri, 24 Jul 2026 14:54:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784904888; cv=none; b=oiawHpAT5qSHSyoyhHbUZhCqVhk4622wPp9P/rWF6I9OJsZCr/QM1DfE/URBiDJYDW+nnDGejh47Q7yJjU52Z703GAnvRP/y+ow5wuTCWIv2hcUrwG1oxGSLgIf6t627dftxzWyELP3rHxIpjlliBjCIlAzANQvKyM5yZMFIZqk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784904888; c=relaxed/simple; bh=ws7pPM5pomNPXyeBV7gKA1VAwCIgldyhmLgZX26cbaM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=E4cbAIL2zRuctKMeJf1feJYGLnzW47oZWVNjr38+EOXuOwM72okOo40t8SYu+N7oa2ik3Bb/+08bBSNGtdMD9I1oDX5uUzdpgSvXpBDm1YUtPjjmsMMdk4QI6a67UFgLQAZmbdymlH0iQlDsBz1h6RkVPXPxfFbDSnQ+KgoLzsc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=PVgn92KN; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="PVgn92KN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1784904882; 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=ws7pPM5pomNPXyeBV7gKA1VAwCIgldyhmLgZX26cbaM=; b=PVgn92KNhGxaj1M4Eph6Cq2+V7bwSEOLvJAhDjwHvxmuVnzN52tKv3sUajK+KuQ/QBDrTd ClMCWLSwy47e7e1z/FbY7iBXD1E1lGXjjlLoaDc36HYsTgaux+R1IuUax8WCWzYI4JDGe+ c2tqOruOpYRRvicXIOHiKMuhtjGr6WI= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-58-g4KwqMnTNcaYHYrg7zyxwA-1; Fri, 24 Jul 2026 10:54:38 -0400 X-MC-Unique: g4KwqMnTNcaYHYrg7zyxwA-1 X-Mimecast-MFC-AGG-ID: g4KwqMnTNcaYHYrg7zyxwA_1784904877 Received: from mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.95]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 399B1180ABE6; Fri, 24 Jul 2026 14:54:36 +0000 (UTC) Received: from fedora (unknown [10.44.33.21]) by mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 35E0215AB; Fri, 24 Jul 2026 14:54:31 +0000 (UTC) Received: by fedora (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 24 Jul 2026 16:54:35 +0200 (CEST) Date: Fri, 24 Jul 2026 16:54:30 +0200 From: Oleg Nesterov To: Mateusz Guzik Cc: Breno Leitao , Christian Brauner , Jens Axboe , Alexander Viro , Jan Kara , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, io-uring@vger.kernel.org, Alexey Gladkov Subject: Re: [PATCH 0/1] pipe: only enable the extra wake_up(rd_wait) when epoll is actually used Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 On 07/24, Mateusz Guzik wrote: > > On Fri, Jul 24, 2026 at 3:58 PM Oleg Nesterov wrote: > > > > This means that io_uring depends on the "nasty semantics" too, io_poll_wake() > > path should add the task work which calls io_req_post_cqe() every time the new > > data arrives, even if the pipe was not empty. > > > > well io_uring could set the flag as well in that case? it does not > inherently mean random select and poll consumers definitely need this. How? I don't think io_uring can do this. It doesn't even know if the file is pipe or not. Only file_operations->poll() does know... __Perhaps__ pipe_poll() could check something like wait->_key & EPOLLET to detect both epoll/io_uring... Not sure, probably not, I'll try to check later. Oleg.