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[64.231.46.127]) by smtp.gmail.com with ESMTPSA id v5sm812398qka.106.2020.04.20.09.05.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2020 09:05:05 -0700 (PDT) Date: Mon, 20 Apr 2020 12:04:58 -0400 (EDT) From: John Kacur X-X-Sender: jkacur@planxty To: Sebastian Andrzej Siewior cc: trix@redhat.com, williams@redhat.com, tglx@linutronix.de, linux-rt-users@vger.kernel.org Subject: Re: [PATCH v2] Import a new test, jitterz In-Reply-To: <20200420134937.fxyjibufftdt6btr@linutronix.de> Message-ID: References: <20200418141449.19293-1-trix@redhat.com> <20200420134937.fxyjibufftdt6btr@linutronix.de> User-Agent: Alpine 2.21 (LFD 202 2017-01-01) MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="-1463806718-757002363-1587398705=:4545" Sender: linux-rt-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1463806718-757002363-1587398705=:4545 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT On Mon, 20 Apr 2020, Sebastian Andrzej Siewior wrote: > On 2020-04-18 07:14:49 [-0700], trix@redhat.com wrote: > > --- /dev/null > > +++ b/src/jitterz/jitterz.c > > @@ -0,0 +1,400 @@ > … > > +/* > > + * jitterz > > + * > > + * Copyright 2019-2020 Tom Rix > > + * > > + */ > > + > > +#ifndef _GNU_SOURCE > > +#define _GNU_SOURCE > > +#endif > > in general there is no need of that ifndef and this should be taken care > by the build system (and refuse the build if _GNU_SOURCE makes no > difference/ is not available). And then include the config.h (or so) > first header file. > In rt-tests, the Makefile already adds this define to the CFLAGS. > > … > > +/* Returns clock ticks */ > > +static inline uint64_t time_stamp_counter(void) > > +{ > > + uint64_t ret = -1; > > +#if defined(__i386__) || defined(__x86_64__) > > + uint32_t l, h; > > + > > + __asm__ __volatile__("lfence"); > > + __asm__ __volatile__("rdtsc" : "=a"(l), "=d"(h)); > > + ret = ((uint64_t)h << 32) | l; > > +#else > > + fprintf(stderr, > > + "Add a time_stamp_counter function for your arch here %s:%d\n", > > + __FILE__, __LINE__); > > + exit(1); > > +#endif > > + return ret; > > +} > > I remember I complained about this in `queuelat' and it ended nowhere > once it got merged. > To repeat my question: Is there a reason not to use clock_gettime()? > With VDSO there should be hardly any difference between this and > clock_gettime(). I would agree with Sebastian there Tom, also easier to maintain. Thanks John ---1463806718-757002363-1587398705=:4545--