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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5A375C4829B for ; Thu, 8 Feb 2024 03:09:05 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rXulA-0007ea-Fp; Wed, 07 Feb 2024 22:07:34 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rXukB-0006ZB-0K for qemu-devel@nongnu.org; Wed, 07 Feb 2024 22:06:32 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rXuk4-0004NM-BB for qemu-devel@nongnu.org; Wed, 07 Feb 2024 22:06:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1707361583; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=cp4T0OV/eWxNPPdn5wej7DTuu59xZM6LTLe/vHPYQB0=; b=JHybcuBgEmNvr9CQ1cEBE3C7R885W007G45WAd+2iGVM2qNA+psIwQxy2Z2UDuVWcEIik+ Nms3oSckHQG2nKagQetc5eJbaw1PpR8TsvOWr7gKjB99iJwjNVy2kdqpq1XBPHAso+k2XZ T2+AaxDBCv068pFUIn+ToopWIDNTM+A= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-358-VsZeWIjlOD2A3XRwGzkBXA-1; Wed, 07 Feb 2024 22:06:20 -0500 X-MC-Unique: VsZeWIjlOD2A3XRwGzkBXA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id 97F0D101FA2C; Thu, 8 Feb 2024 03:06:19 +0000 (UTC) Received: from x1n.redhat.com (unknown [10.72.116.45]) by smtp.corp.redhat.com (Postfix) with ESMTP id 405E3492BC7; Thu, 8 Feb 2024 03:06:16 +0000 (UTC) From: peterx@redhat.com To: Peter Maydell , qemu-devel@nongnu.org Cc: peterx@redhat.com, Fabiano Rosas Subject: [PULL 15/34] migration/multifd: Forbid spurious wakeups Date: Thu, 8 Feb 2024 11:05:09 +0800 Message-ID: <20240208030528.368214-16-peterx@redhat.com> In-Reply-To: <20240208030528.368214-1-peterx@redhat.com> References: <20240208030528.368214-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.106, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Peter Xu Now multifd's logic is designed to have no spurious wakeup. I still remember a talk to Juan and he seems to agree we should drop it now, and if my memory was right it was there because multifd used to hit that when still debugging. Let's drop it and see what can explode; as long as it's not reaching soft-freeze. Reviewed-by: Fabiano Rosas Link: https://lore.kernel.org/r/20240202102857.110210-15-peterx@redhat.com Signed-off-by: Peter Xu --- migration/multifd.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/migration/multifd.c b/migration/multifd.c index 6aa44340de..28b54100cd 100644 --- a/migration/multifd.c +++ b/migration/multifd.c @@ -756,7 +756,9 @@ static void *multifd_send_thread(void *opaque) p->next_packet_size = 0; qatomic_set(&p->pending_job, false); qemu_mutex_unlock(&p->mutex); - } else if (qatomic_read(&p->pending_sync)) { + } else { + /* If not a normal job, must be a sync request */ + assert(qatomic_read(&p->pending_sync)); p->flags = MULTIFD_FLAG_SYNC; multifd_send_fill_packet(p); ret = qio_channel_write_all(p->c, (void *)p->packet, @@ -771,9 +773,6 @@ static void *multifd_send_thread(void *opaque) qatomic_set(&p->pending_sync, false); qemu_mutex_unlock(&p->mutex); qemu_sem_post(&p->sem_sync); - } else { - qemu_mutex_unlock(&p->mutex); - /* sometimes there are spurious wakeups */ } } -- 2.43.0