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 X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 87816C33CAC for ; Thu, 6 Feb 2020 17:33:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5FFEC21741 for ; Thu, 6 Feb 2020 17:33:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fCyqbDTD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727479AbgBFRdz (ORCPT ); Thu, 6 Feb 2020 12:33:55 -0500 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:57201 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726990AbgBFRdz (ORCPT ); Thu, 6 Feb 2020 12:33:55 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1581010433; 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=BklOOZtpEbXR2lfLsVN/Nzs8K2IHl/5W7tD5xZRKzIw=; b=fCyqbDTD/T5hSfkDtrAEZC1uLCzzJ1YGwiR/kfuYPy+dzgGfznVbW2dsRTxHP+yzxNQSwV IcagDAzaZGd80KHiMXlyUhhSSP0JzDcXh0bFJCtyHFliasz/r9Ss19YOISnktovOfXLLlN Lqat+iSpMXoILSQ3393HLh393fd4v6I= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-377-ax0HIhwfOJOVFTUXq1Cpgw-1; Thu, 06 Feb 2020 12:33:52 -0500 X-MC-Unique: ax0HIhwfOJOVFTUXq1Cpgw-1 Received: by mail-wr1-f69.google.com with SMTP id s13so3829259wrb.21 for ; Thu, 06 Feb 2020 09:33:51 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=BklOOZtpEbXR2lfLsVN/Nzs8K2IHl/5W7tD5xZRKzIw=; b=eIamBWGUn7oYEy+EU6b7mv67DhCimzOfoDVwSzd1BZDtwdOozOxrtyB6VRpxnaCq37 BT0JqWNPkX1kSUcHIxN/jhps57Ob9mdQRISvi97UfDwMKfeIOW+OobHdY6bBqEubW6x/ OR1LjVv+1ym6pJab+co0xuAOgTCwvPRFylYQElv/MxVYmBXNQ2lVka1EA/AcNNP9HNkE 3EBlVUgtlHsBwxBqzdyl42vPFFin3SsNtXYFqZEs6OEHUVwdkJJJ7mx5DE0NTUHIt4JM dDZkl6WoaCqkfFqO86l65lJEHmipgjCOunz3dju6rWbwgL3FKmrWMF9/h80/WXYrOmep X6MQ== X-Gm-Message-State: APjAAAUc78oBGxM0WxlbEBlbzBjO/kuq97KM1kzL1/4/0rULPr3zKfN8 hXogsA4UPBhdRf6Wo28s70tN8AbWOZbzE7MmUYFV7i/W2HJxlknMm+QkaXNNM/sjXjYaux9I8JO L4u/aia85W78hWksaoMY= X-Received: by 2002:a1c:7915:: with SMTP id l21mr5504744wme.112.1581010431052; Thu, 06 Feb 2020 09:33:51 -0800 (PST) X-Google-Smtp-Source: APXvYqz/LgvjhDqPglzyKZz65I/FvXOuZVvP6MOg0sTKNxQjVoAU4NrjaJmmLB1IwT7DfEihNiQf7w== X-Received: by 2002:a1c:7915:: with SMTP id l21mr5504712wme.112.1581010430684; Thu, 06 Feb 2020 09:33:50 -0800 (PST) Received: from steredhat (host209-4-dynamic.27-79-r.retail.telecomitalia.it. [79.27.4.209]) by smtp.gmail.com with ESMTPSA id z133sm263777wmb.7.2020.02.06.09.33.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Feb 2020 09:33:50 -0800 (PST) Date: Thu, 6 Feb 2020 18:33:48 +0100 From: Stefano Garzarella To: Jens Axboe Cc: linux-kernel@vger.kernel.org, io-uring@vger.kernel.org Subject: Re: [PATCH liburing v2 0/1] test: add epoll test case Message-ID: References: <20200131142943.120459-1-sgarzare@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Fri, Jan 31, 2020 at 4:39 PM Jens Axboe wrote: > > On 1/31/20 7:29 AM, Stefano Garzarella wrote: > > Hi Jens, > > this is a v2 of the epoll test. > > > > v1 -> v2: > > - if IORING_FEAT_NODROP is not available, avoid to overflow the CQ > > - add 2 new tests to test epoll with IORING_FEAT_NODROP > > - cleanups > > > > There are 4 sub-tests: > > 1. test_epoll > > 2. test_epoll_sqpoll > > 3. test_epoll_nodrop > > 4. test_epoll_sqpoll_nodrop > > > > In the first 2 tests, I try to avoid to queue more requests than we have room > > for in the CQ ring. These work fine, I have no faults. > > Thanks! > > > In the tests 3 and 4, if IORING_FEAT_NODROP is supported, I try to submit as > > much as I can until I get a -EBUSY, but they often fail in this way: > > the submitter manages to submit everything, the receiver receives all the > > submitted bytes, but the cleaner loses completion events (I also tried to put a > > timeout to epoll_wait() in the cleaner to be sure that it is not related to the > > patch that I send some weeks ago, but the situation doesn't change, it's like > > there is still overflow in the CQ). > > > > Next week I'll try to investigate better which is the problem. > > Does it change if you have an io_uring_enter() with GETEVENTS set? I wonder if > you just pruned the CQ ring but didn't flush the internal side. If I do io_uring_enter() with GETEVENTS set and wait_nr = 0 it solves the issue, I think because we call io_cqring_events() that flushes the overflow list. At this point, should we call io_cqring_events() (that flushes the overflow list) in io_uring_poll()? I mean something like this: diff --git a/fs/io_uring.c b/fs/io_uring.c index 77f22c3da30f..2769451af89a 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -6301,7 +6301,7 @@ static __poll_t io_uring_poll(struct file *file, poll_table *wait) if (READ_ONCE(ctx->rings->sq.tail) - ctx->cached_sq_head != ctx->rings->sq_ring_entries) mask |= EPOLLOUT | EPOLLWRNORM; - if (READ_ONCE(ctx->rings->cq.head) != ctx->cached_cq_tail) + if (!io_cqring_events(ctx, false)) mask |= EPOLLIN | EPOLLRDNORM; return mask; Thanks, Stefano