From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <jianbo.liu@linaro.org> Received: from mail-yw0-f174.google.com (mail-yw0-f174.google.com [209.85.161.174]) by dpdk.org (Postfix) with ESMTP id 5F0A43777 for <dev@dpdk.org>; Thu, 5 Jan 2017 07:47:28 +0100 (CET) Received: by mail-yw0-f174.google.com with SMTP id t125so334737015ywc.1 for <dev@dpdk.org>; Wed, 04 Jan 2017 22:47:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=XJKKQKOmdm5Z268TPdbkfk8YCwCEJvmU6oufKtRLZxk=; b=PXydvE4p7hUFDqZH4haL4MBQsDQQfJvjgXJKozygZAJ7f8UuOUgM13nMZ/dKmA+TSH FQB1kH3iKLGLqwF3EOVWwobOtPrBDYAv0s106BErbHW9fKtz0fCU15tCC0lHRvnxqWTR UEStoNQsOoGiTnIXIGa3qTBZIUQzVkRWrkxHg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=XJKKQKOmdm5Z268TPdbkfk8YCwCEJvmU6oufKtRLZxk=; b=mEzX2UCnyknqAyMeEaT3xqa8gmcXpCtcJNKaIHNgDtGMq4miDvmK6EEPbB0O9UzX0l nhIuuRBOiWF4Axv4Y3rYtW1v32XL+BEl39jcKOuiK7Bj0jycgFaHiJjI7dRuTqD6ldUX kAmUfJIRqyFHVU0QdXJw40q79fKsCgqmi/b5lYB5bdmrLn7/UaqWk46vx8K4aA5YWhTi FbpymDtFIKAJhGzx3Bk0rSUlt6RNCJ4rag/puezw0mmqoQtAL9/xU2BqC7WpASiADDUL sS6R5a3a4WIAg75WgLs5rkCV4vUSWebj4hT9QFKkTCdPjVCVsrJU1vtfCJ6DQgGh94ps yymw== X-Gm-Message-State: AIkVDXJwzjZjw2zNjrjtw8TFHa2EpUL8O+2tRR7VUcCC8exjiClf/FqJH4LD+yRta9wJRMBAftYq+IzLU5SfSCGa X-Received: by 10.129.138.67 with SMTP id a64mr65656531ywg.43.1483598847568; Wed, 04 Jan 2017 22:47:27 -0800 (PST) MIME-Version: 1.0 Received: by 10.37.221.65 with HTTP; Wed, 4 Jan 2017 22:47:27 -0800 (PST) In-Reply-To: <20170105062430.GA14618@localhost.localdomain> References: <1481680558-4003-1-git-send-email-jerin.jacob@caviumnetworks.com> <1482832175-27199-1-git-send-email-jerin.jacob@caviumnetworks.com> <1482832175-27199-10-git-send-email-jerin.jacob@caviumnetworks.com> <CAP4Qi38GTrKaUsxCWFH9g8D=wiR1wBM9N5HGykya5pKoOfen3g@mail.gmail.com> <20170104100104.GA6578@localhost.localdomain> <CAP4Qi3-r80hfY2Sj5sHVWJFe+ubYDQ4=91OMDme8zGzBibjT9w@mail.gmail.com> <20170105062430.GA14618@localhost.localdomain> From: Jianbo Liu <jianbo.liu@linaro.org> Date: Thu, 5 Jan 2017 14:47:27 +0800 Message-ID: <CAP4Qi38t+oNR1jQnOyoVG9Upz-TpS3G2pZGZOutoHjJF_c_uOw@mail.gmail.com> To: Jerin Jacob <jerin.jacob@caviumnetworks.com> Cc: dev@dpdk.org, "Ananyev, Konstantin" <konstantin.ananyev@intel.com>, Thomas Monjalon <thomas.monjalon@6wind.com>, Bruce Richardson <bruce.richardson@intel.com>, Jan Viktorin <viktorin@rehivetech.com>, Santosh Shukla <santosh.shukla@caviumnetworks.com>, David Marchand <david.marchand@6wind.com> Content-Type: text/plain; charset=UTF-8 Subject: Re: [dpdk-dev] [PATCH v2 09/29] eal/arm64: define I/O device memory barriers for arm64 X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions <dev.dpdk.org> List-Unsubscribe: <http://dpdk.org/ml/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://dpdk.org/ml/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <http://dpdk.org/ml/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> X-List-Received-Date: Thu, 05 Jan 2017 06:47:28 -0000 On 5 January 2017 at 14:24, Jerin Jacob <jerin.jacob@caviumnetworks.com> wrote: > On Thu, Jan 05, 2017 at 01:31:44PM +0800, Jianbo Liu wrote: >> On 4 January 2017 at 18:01, Jerin Jacob <jerin.jacob@caviumnetworks.com> wrote: >> > On Tue, Jan 03, 2017 at 03:48:32PM +0800, Jianbo Liu wrote: >> >> On 27 December 2016 at 17:49, Jerin Jacob >> >> <jerin.jacob@caviumnetworks.com> wrote: >> >> > CC: Jianbo Liu <jianbo.liu@linaro.org> >> >> > Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com> >> >> > --- >> >> > lib/librte_eal/common/include/arch/arm/rte_atomic_64.h | 6 ++++++ >> >> > 1 file changed, 6 insertions(+) >> >> > >> >> > diff --git a/lib/librte_eal/common/include/arch/arm/rte_atomic_64.h b/lib/librte_eal/common/include/arch/arm/rte_atomic_64.h >> >> > index 78ebea2..ef0efc7 100644 >> >> > --- a/lib/librte_eal/common/include/arch/arm/rte_atomic_64.h >> >> > +++ b/lib/librte_eal/common/include/arch/arm/rte_atomic_64.h >> >> > @@ -88,6 +88,12 @@ static inline void rte_rmb(void) >> >> > >> >> > #define rte_smp_rmb() dmb(ishld) >> >> > >> >> > +#define rte_io_mb() rte_mb() >> >> > + >> >> > +#define rte_io_wmb() rte_wmb() >> >> > + >> >> > +#define rte_io_rmb() rte_rmb() >> >> > + >> >> >> >> I think it's better to use outer shareable dmb for io barrier, instead of dsb. >> > >> > Its is difficult to generalize. AFAIK, from the IO barrier perspective >> > dsb would be the right candidate. But just for the DMA barrier between IO may >> > be outer sharable dmb is enough. In-terms of performance implication, the >> > fastpath code(door bell write) has been changed to relaxed write in all >> > the drivers in this patchset and rte_io_* will be only >> > used by rte_[read/write]8/16/32/64 which will be in slow-path. >> > So, IMO, it better stick with dsb and its safe from the complete IO barrier >> > perspective. >> >> If so, why not use *mb() directly? > > Adding David Marchand, EAL Maintainer. > > Instead of rte_io_?. I thought, IO specific constraints can be abstracted > here in rte_io_*. Apart from arm, there other arch like "arc" has similar > constraints. IMHO, no harm in keeping that abstraction. > > Thoughts ? > > http://lxr.free-electrons.com/ident?i=__iormb > >> >> > >> > At least on ThunderX, I couldn't see any performance difference between >> > using dsb(st) and dmb(oshst) for dma write barrier before the doorbell register >> > write in fastpath. In case there are platforms which has such performance difference, >> > may be could add rte_dma_wmb() and rte_dma_rmb() in future like Linux kernel >> > dma_wmb() and dma_rmb().(But i couldn't see all the driver are using it, >> > though) >> > >> >> But there is no io_*mb() in the kernel, so you want to be different? > > It is their for arm,arm64,arc architectures in Linux kernel. Please check writel > implementation for arm64 > > http://lxr.free-electrons.com/source/arch/arm64/include/asm/io.h#L143 > Yes, I knew. But I'm afraid it will be mixed with dma_*mb by someone else.