From nobody Tue Nov 30 17:08:08 2021 X-Original-To: dev-commits-src-main@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 5107618CDD63; Tue, 30 Nov 2021 17:08:17 +0000 (UTC) (envelope-from avg@freebsd.org) Received: from smtp.freebsd.org (smtp.freebsd.org [96.47.72.83]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4J3TFF0R4Qz4gJH; Tue, 30 Nov 2021 17:08:17 +0000 (UTC) (envelope-from avg@freebsd.org) Received: from [192.168.0.88] (unknown [195.64.148.76]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: avg/mail) by smtp.freebsd.org (Postfix) with ESMTPSA id 4CBEB7846; Tue, 30 Nov 2021 17:08:16 +0000 (UTC) (envelope-from avg@freebsd.org) Message-ID: <69d4804d-1d94-7757-5c93-0d062f9c31c0@FreeBSD.org> Date: Tue, 30 Nov 2021 19:08:08 +0200 List-Id: Commit messages for the main branch of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-main List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-main@freebsd.org X-BeenThere: dev-commits-src-main@freebsd.org MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:91.0) Gecko/20100101 Firefox/91.0 Thunderbird/91.3.0 From: Andriy Gapon Subject: Re: git: 3d9d64aa1846 - main - kern_tc: unify timecounter to bintime delta conversion Content-Language: en-US To: Kyle Evans Cc: src-committers , dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org References: <202111301334.1AUDYJEU014078@gitrepo.freebsd.org> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1638292097; 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=zLRxYFUzZlAAFShGctbdXY3v3ALZn03qmIKRlizpDsE=; b=xEYJUzOGnhxkc5IWmzsnuIdu+11VS0aQKU7VEIzzfozZEnEFdfnD6+0WgMI69hHrQPP95f oz7ZYxmmWrX4S3zKGfTQjcOJqhV2VW1SSflWFFrau+DgjEn0pvgadyjbrWcEgFLW82Plmo v1CxMJ/G4uzHbEWXl8OV/VWeDCMWU4yWeDp5yArenGTgCEwCuM3VKM4RzBXfu0GFLACqBY QT5aojeCbXOrAHd+d3l6HILMWwn1Ddri+9zfNA8YaPDBQi59r7qrAb66YPrR9DlqQZHYb8 UDLjmcvIAmTm5s8W+lYBgj63L5wCRBU69oR4G8gWmB1gaFTXVHI/m/AFesQS7A== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1638292097; a=rsa-sha256; cv=none; b=OH5umLSC3PqitvAEzCNKaUfNnlVeXM206tE5jjf4WJL1v6D8+HbOEe3HVXch3BA1yRAKMG ul3c5C12K0JJ6pi+Z2KXeyAlSgGjIxG2UJPpOIAAcpWu/A9xn6x6+E1sGISS/5KSFINLuM E838uBzlJb9jJBk55ke38cp3OTlVpjVreAboS2WE9/ztP4I+AOkPGE7zNv17A8Et4SjXII HRRN25AlwfPg2L0Gj2f1S4+c5SdV6Q4pXbgAjknLGJmtsWzAFIEBclwbuFz4ui7qt4oEba nTZfBiHZiEzbIF6+YbvCe7SRD+/ZjVkB2w9zsN6DDPfdIF6vmdqz8Get6ohqsg== ARC-Authentication-Results: i=1; mx1.freebsd.org; none X-ThisMailContainsUnwantedMimeParts: N On 30/11/2021 18:14, Kyle Evans wrote: > I wonder if this helps explain the behavior we saw when enabling TSC > on VirtualBox guests. Threads doing small ~1 second or less sleeps > would start to miss their wakeups, so we'd consistently see, e.g., > shutdown issues after applying a high loading while we're waiting for > bufdaemon threads. It very well may be the case. The reason I arrived at this change is that we also sometimes saw the same problem but on VMWware. That prompted me to add some diagnostic code to sleepqueue to turn those missed wakeups into panics. As kib pointed out, mav recently made a change that would mask the problem as a side effect: https://cgit.FreeBSD.org/src/commit/?id=6df1359e5542f69179c142be1ea099d447e273d1 But I wanted to fix the root cause anyway. -- Andriy Gapon