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([2a0c:5a80:3c10:3400:3c70:6643:6e71:7eae]) by smtp.gmail.com with ESMTPSA id a10sm4350726wmq.27.2021.11.24.01.45.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Nov 2021 01:45:45 -0800 (PST) Message-ID: <482c55bc52b17c4ddf113a75acaca73a0c0a7b9b.camel@redhat.com> Subject: Re: [RFC PATCH 1/2] arm64/tracing: add cntvct based trace clock From: Nicolas Saenz Julienne To: Steven Rostedt Cc: linux-arm-kernel@lists.infradead.org, maz@kernel.org, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, catalin.marinas@arm.com, will@kernel.org, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu, mingo@redhat.com, mtosatti@redhat.com, nilal@redhat.com, Linux Trace Devel Date: Wed, 24 Nov 2021 10:45:44 +0100 In-Reply-To: <20211122095735.2340f38f@gandalf.local.home> References: <20211119102117.22304-1-nsaenzju@redhat.com> <20211119102117.22304-2-nsaenzju@redhat.com> <20211122095735.2340f38f@gandalf.local.home> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.42.1 (3.42.1-1.fc35) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org On Mon, 2021-11-22 at 09:57 -0500, Steven Rostedt wrote: > On Fri, 19 Nov 2021 11:21:17 +0100 > Nicolas Saenz Julienne wrote: > > > +/* SPDX-License-Identifier: GPL-2.0 */ > > +#ifndef _ASM_ARM64_TRACE_CLOCK_H > > +#define _ASM_ARM64_TRACE_CLOCK_H > > + > > +#include > > + > > +extern u64 notrace trace_clock_arm64_cntvct(void); > > + > > +# define ARCH_TRACE_CLOCKS \ > > + { trace_clock_arm64_cntvct, "cntvct", .in_ns = 0 }, > > + > > +#endif /* _ASM_ARM64_TRACE_CLOCK_H */ > > So this will appear as a usable clock in trace-cmd. > > And since this will be used to synchronize between host and guest like the > x86_tsc is used, that means that trace-cmd needs to know that this is the > an arch "CPU" clock. I wonder if we should rename x86_clock (or at least > make it an alias) to "kvm_clock". Then we can have trace-cmd use > "kvm_clock" as the clock for synchronization between host and guests for > all architectures? > > Thinking about this, instead of renaming it, I'll add code to create an > alias to these clocks. Then every arch can pick what clock is used that is > the same between hosts and guests such that user space tooling doesn't have > to keep a database of what clocks are used for synchronization between > hosts and guests for each arch. > > I'll go add some code ;-) I really like the idea, please keep me in the loop if you send something upstream. -- Nicolás Sáenz 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 71A82C433F5 for ; Wed, 24 Nov 2021 09:47:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Date:Cc:To:From:Subject:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=tBRHtYRX9buTQjXbBmTqChnTLxO8wNT46mryKqH2yYk=; b=HLVvJMbYKoy+3j j8GfleujV4J94YMXr4brpktQEkktDAzsKUbW6fRpQoenAEjz1El/w9o5ISbeJGF31rtZ0WWsv/b9X zaEYvQGi40EiteMZmZNwABIaBwQdgFfLCqz8RipMXDpYHBtIQvYS9rigAFKoXGIWx7Jeh9/dzkFby eGa6quAyGWQ1RyFtg34RKCT79skdDDLvQwiZKhW+mkykEdQ/eWSUMzXO4EhVLKAEpxwDaUP6YH4LE u7qJ15PMggqEgn2miCBvE8gmXo+8Mqk9UEJhZUOuw6cH9MnrGWtg52hzVYsifbvbx1KfRqnGMPfoD 2MXNL9Gt4k2368RyObiA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mpoqi-004QDC-9c; Wed, 24 Nov 2021 09:45:56 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mpoqe-004QC9-Nf for linux-arm-kernel@lists.infradead.org; Wed, 24 Nov 2021 09:45:54 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1637747150; 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=/ocPRPURvuCP4fzE5T0eVQSQIxy0gRmJcpuXxwEQtHM=; b=LuyqBbFtujkWGzN+UyHT/iUhvvFcQ/+tjIEMT3o+aT9nu8RbgIpSXLPza0kuaFTTq8gKcD X5dcpDs39dAdIdf0r+b5QRHLIXMG2uxLR4Wh5Bmp1baIzXlbicBXJESZhVKhXq9+VS0djW lpFBgqMXBd+YP8Hbqp9nPAZqfcQ1afo= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-105-DsQth4CYOEq-kb3k6542_A-1; Wed, 24 Nov 2021 04:45:46 -0500 X-MC-Unique: DsQth4CYOEq-kb3k6542_A-1 Received: by mail-wm1-f70.google.com with SMTP id l4-20020a05600c1d0400b00332f47a0fa3so1098181wms.8 for ; Wed, 24 Nov 2021 01:45:46 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=/ocPRPURvuCP4fzE5T0eVQSQIxy0gRmJcpuXxwEQtHM=; b=mSxiYmcrnjYRmg7CooiJkCdnI0lbkBPlKUb7L7qrL0iliTV6JR+wdAlpUZr02xtKC9 0kIap49cPuklik8Wf95G92WomEWr8KjeIeGGpYQhmVvv5+48DN86xoPswJIxx//S98AE bsunfol+73N91nKDHUA1yBRUaKq4dG/1OzYASu4mXbUHm7Detk2stlq+egM0pFKF9zxO EhgpY8djHY0O725nQFYomPj39A3ho/ie3bcBpDR4TiY1iHz/IsRmguejJX1jRoJ/5mIN /o3IA1aG2273b/x2LKkSchLTwR8sR3oXH7qM/v73punEiQ3hXwmoVV5V8m68y1/s+TgH Y1eQ== X-Gm-Message-State: AOAM530PyJiN0v7QpcGZqYHnHjX97Nb0tYrh34cKlM4oh3OkUzd+NRWl EcHlqkr8lDdboM/ckIyX4vNRxyHfBjiH25WEHy7b36w3l9j0MfJvfVq3Hza6v07QhX7VzuKReOk Nw3Mi1WCMUZCoq5Ivh8KBr5i/kTRQofGS4Iw= X-Received: by 2002:a5d:58f9:: with SMTP id f25mr17470492wrd.206.1637747145588; Wed, 24 Nov 2021 01:45:45 -0800 (PST) X-Google-Smtp-Source: ABdhPJwP0zHgPBVMJ6rnPoEJ8gNRRURG0BefwNCQkWdV/Pp5YgDYW6ukSyMMP2OQX0rFvd7bFyHeUw== X-Received: by 2002:a5d:58f9:: with SMTP id f25mr17470474wrd.206.1637747145442; Wed, 24 Nov 2021 01:45:45 -0800 (PST) Received: from ?IPv6:2a0c:5a80:3c10:3400:3c70:6643:6e71:7eae? ([2a0c:5a80:3c10:3400:3c70:6643:6e71:7eae]) by smtp.gmail.com with ESMTPSA id a10sm4350726wmq.27.2021.11.24.01.45.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Nov 2021 01:45:45 -0800 (PST) Message-ID: <482c55bc52b17c4ddf113a75acaca73a0c0a7b9b.camel@redhat.com> Subject: Re: [RFC PATCH 1/2] arm64/tracing: add cntvct based trace clock From: Nicolas Saenz Julienne To: Steven Rostedt Cc: linux-arm-kernel@lists.infradead.org, maz@kernel.org, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, catalin.marinas@arm.com, will@kernel.org, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu, mingo@redhat.com, mtosatti@redhat.com, nilal@redhat.com, Linux Trace Devel Date: Wed, 24 Nov 2021 10:45:44 +0100 In-Reply-To: <20211122095735.2340f38f@gandalf.local.home> References: <20211119102117.22304-1-nsaenzju@redhat.com> <20211119102117.22304-2-nsaenzju@redhat.com> <20211122095735.2340f38f@gandalf.local.home> User-Agent: Evolution 3.42.1 (3.42.1-1.fc35) MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=nsaenzju@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211124_014552_889340_A642B1FA X-CRM114-Status: GOOD ( 20.04 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gTW9uLCAyMDIxLTExLTIyIGF0IDA5OjU3IC0wNTAwLCBTdGV2ZW4gUm9zdGVkdCB3cm90ZToK PiBPbiBGcmksIDE5IE5vdiAyMDIxIDExOjIxOjE3ICswMTAwCj4gTmljb2xhcyBTYWVueiBKdWxp ZW5uZSA8bnNhZW56anVAcmVkaGF0LmNvbT4gd3JvdGU6Cj4gCj4gPiArLyogU1BEWC1MaWNlbnNl LUlkZW50aWZpZXI6IEdQTC0yLjAgKi8KPiA+ICsjaWZuZGVmIF9BU01fQVJNNjRfVFJBQ0VfQ0xP Q0tfSAo+ID4gKyNkZWZpbmUgX0FTTV9BUk02NF9UUkFDRV9DTE9DS19ICj4gPiArCj4gPiArI2lu Y2x1ZGUgPGxpbnV4L3R5cGVzLmg+Cj4gPiArCj4gPiArZXh0ZXJuIHU2NCBub3RyYWNlIHRyYWNl X2Nsb2NrX2FybTY0X2NudHZjdCh2b2lkKTsKPiA+ICsKPiA+ICsjIGRlZmluZSBBUkNIX1RSQUNF X0NMT0NLUyBcCj4gPiArCXsgdHJhY2VfY2xvY2tfYXJtNjRfY250dmN0LCAiY250dmN0IiwgLmlu X25zID0gMCB9LAo+ID4gKwo+ID4gKyNlbmRpZiAgLyogX0FTTV9BUk02NF9UUkFDRV9DTE9DS19I ICovCj4gCj4gU28gdGhpcyB3aWxsIGFwcGVhciBhcyBhIHVzYWJsZSBjbG9jayBpbiB0cmFjZS1j bWQuCj4gCj4gQW5kIHNpbmNlIHRoaXMgd2lsbCBiZSB1c2VkIHRvIHN5bmNocm9uaXplIGJldHdl ZW4gaG9zdCBhbmQgZ3Vlc3QgbGlrZSB0aGUKPiB4ODZfdHNjIGlzIHVzZWQsIHRoYXQgbWVhbnMg dGhhdCB0cmFjZS1jbWQgbmVlZHMgdG8ga25vdyB0aGF0IHRoaXMgaXMgdGhlCj4gYW4gYXJjaCAi Q1BVIiBjbG9jay4gSSB3b25kZXIgaWYgd2Ugc2hvdWxkIHJlbmFtZSB4ODZfY2xvY2sgKG9yIGF0 IGxlYXN0Cj4gbWFrZSBpdCBhbiBhbGlhcykgdG8gImt2bV9jbG9jayIuIFRoZW4gd2UgY2FuIGhh dmUgdHJhY2UtY21kIHVzZQo+ICJrdm1fY2xvY2siIGFzIHRoZSBjbG9jayBmb3Igc3luY2hyb25p emF0aW9uIGJldHdlZW4gaG9zdCBhbmQgZ3Vlc3RzIGZvcgo+IGFsbCBhcmNoaXRlY3R1cmVzPwo+ Cj4gVGhpbmtpbmcgYWJvdXQgdGhpcywgaW5zdGVhZCBvZiByZW5hbWluZyBpdCwgSSdsbCBhZGQg Y29kZSB0byBjcmVhdGUgYW4KPiBhbGlhcyB0byB0aGVzZSBjbG9ja3MuIFRoZW4gZXZlcnkgYXJj aCBjYW4gcGljayB3aGF0IGNsb2NrIGlzIHVzZWQgdGhhdCBpcwo+IHRoZSBzYW1lIGJldHdlZW4g aG9zdHMgYW5kIGd1ZXN0cyBzdWNoIHRoYXQgdXNlciBzcGFjZSB0b29saW5nIGRvZXNuJ3QgaGF2 ZQo+IHRvIGtlZXAgYSBkYXRhYmFzZSBvZiB3aGF0IGNsb2NrcyBhcmUgdXNlZCBmb3Igc3luY2hy b25pemF0aW9uIGJldHdlZW4KPiBob3N0cyBhbmQgZ3Vlc3RzIGZvciBlYWNoIGFyY2guCj4gCj4g SSdsbCBnbyBhZGQgc29tZSBjb2RlIDstKQoKSSByZWFsbHkgbGlrZSB0aGUgaWRlYSwgcGxlYXNl IGtlZXAgbWUgaW4gdGhlIGxvb3AgaWYgeW91IHNlbmQgc29tZXRoaW5nCnVwc3RyZWFtLgoKLS0g Ck5pY29sw6FzIFPDoWVuegoKCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fCmxpbnV4LWFybS1rZXJuZWwgbWFpbGluZyBsaXN0CmxpbnV4LWFybS1rZXJuZWxA bGlzdHMuaW5mcmFkZWFkLm9yZwpodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xp c3RpbmZvL2xpbnV4LWFybS1rZXJuZWwK