From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by dpdk.org (Postfix) with ESMTP id BF6B625D9 for ; Thu, 9 Aug 2018 13:31:02 +0200 (CEST) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Aug 2018 04:31:01 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,214,1531810800"; d="scan'208";a="253340186" Received: from fyigit-mobl.ger.corp.intel.com (HELO [172.28.47.193]) ([172.28.47.193]) by fmsmga006.fm.intel.com with ESMTP; 09 Aug 2018 04:30:58 -0700 To: Kiran Kumar Cc: dev@dpdk.org, Jerin Jacob , Konstantin Ananyev , Bruce Richardson , Santosh Shukla References: <1533810233-7706-1-git-send-email-kkokkilagadda@caviumnetworks.com> From: Ferruh Yigit Openpgp: preference=signencrypt Autocrypt: addr=ferruh.yigit@intel.com; prefer-encrypt=mutual; keydata= xsFNBFXZCFABEADCujshBOAaqPZpwShdkzkyGpJ15lmxiSr3jVMqOtQS/sB3FYLT0/d3+bvy qbL9YnlbPyRvZfnP3pXiKwkRoR1RJwEo2BOf6hxdzTmLRtGtwWzI9MwrUPj6n/ldiD58VAGQ +iR1I/z9UBUN/ZMksElA2D7Jgg7vZ78iKwNnd+vLBD6I61kVrZ45Vjo3r+pPOByUBXOUlxp9 GWEKKIrJ4eogqkVNSixN16VYK7xR+5OUkBYUO+sE6etSxCr7BahMPKxH+XPlZZjKrxciaWQb +dElz3Ab4Opl+ZT/bK2huX+W+NJBEBVzjTkhjSTjcyRdxvS1gwWRuXqAml/sh+KQjPV1PPHF YK5LcqLkle+OKTCa82OvUb7cr+ALxATIZXQkgmn+zFT8UzSS3aiBBohg3BtbTIWy51jNlYdy ezUZ4UxKSsFuUTPt+JjHQBvF7WKbmNGS3fCid5Iag4tWOfZoqiCNzxApkVugltxoc6rG2TyX CmI2rP0mQ0GOsGXA3+3c1MCdQFzdIn/5tLBZyKy4F54UFo35eOX8/g7OaE+xrgY/4bZjpxC1 1pd66AAtKb3aNXpHvIfkVV6NYloo52H+FUE5ZDPNCGD0/btFGPWmWRmkPybzColTy7fmPaGz cBcEEqHK4T0aY4UJmE7Ylvg255Kz7s6wGZe6IR3N0cKNv++O7QARAQABzSVGZXJydWggWWln aXQgPGZlcnJ1aC55aWdpdEBpbnRlbC5jb20+wsF+BBMBAgAoAhsDBgsJCAcDAgYVCAIJCgsE FgIDAQIeAQIXgAUCWZR3VQUJB33WBQAKCRD5M+tD3xNhH6DWEACVhEb8q1epPwZrUDoxzu7E TS1b8tmabOmnjXZRs6+EXgUVHkp2xxkCfDmL3pa5bC0G/74aJnWjNsdvE05V1cb4YK4kRQ62 FwDQ+hlrFrwFB3PtDZk1tpkzCRHvJgnIil+0MuEh32Y57ig6hy8yO8ql7Lohyrnpfk/nNpm4 jQGEF5qEeHcEFe1AZQlPHN/STno8NZSz2nl0b2cw+cujN1krmvB52Ah/2KugQ6pprVyrGrzB c34ZQO9OsmSjJlETCZk6EZzuhfe16iqBFbOSadi9sPcJRwaUQBid+xdFWl7GQ8qC3zNPibSF HmU43yBZUqJDZlhIcl6/cFpOSjv2sDWdtjEXTDn5y/0FsuY0mFE78ItC4kCTIVk17VZoywcd fmbbnwOSWzDq7hiUYuQGkIudJw5k/A1CMsyLkoUEGN3sLfsw6KASgS4XrrmPO4UVr3mH5bP1 yC7i1OVNpzvOxtahmzm481ID8sk72GC2RktTOHb0cX+qdoiMMfYgo3wRRDYCBt6YoGYUxF1p msjocXyqToKhhnFbXLaZlVfnQ9i2i8jsj9SKig+ewC2p3lkPj6ncye9q95bzhmUeJO6sFhJg Hiz6syOMg8yCcq60j07airybAuHIDNFWk0gaWAmtHZxLObZx2PVn2nv9kLYGohFekw0AOsIW ta++5m48dnCoAc7BTQRX1ky+ARAApzQNvXvE2q1LAS+Z+ni2R13Bb1cDS1ZYq1jgpR13+OKN ipzd8MPngRJilXxBaPTErhgzR0vGcNTYhjGMSyFIHVOoBq1VbP1a0Fi/NqWzJOowo/fDfgVy K4vuitc/gCJs+2se4hdZA4EQJxVlNM51lgYDNpjPGIA43MX15OLAip73+ho6NPBMuc5qse3X pAClNhBKfENRCWN428pi3WVkT+ABRTE0taxjJNP7bb+9TQYNRqGwnGzX5/XISv44asWIQCaq vOkXSUJLd//cdVNTqtL1wreCVVR5pMXj7VIrlk07fmmJVALCmGbFr53BMb8O+8dgK2A5mitM n44d+8KdJWOwziRxcaMk/LclmZS3Iv1TERtiWt98Y9AjeAtcgYPkA3ld0BcUKONogP8pHVz1 Ed3s5rDQ91yr1S0wuAzW91fxGUO4wY+uPmxCtFVuBgd9VT9NAKTUL0qHM7CDgCnZPe0TW6Zj 8OqtdCCyAfvU9cW5xWM7Icxhde6AtPxhDSBwE8fL2ZmrDmaA4jmUKXp3i4JxRPSX84S08b+s DWXHPxy10UFU5A7EK/BEbZAKBwn9ROfm+WK+6X5xOGLoRE++OqNuUudxC1GDyLOPaqCbBCS9 +P6HsTHzxsjyJa27n4jcrcuY3P9TEcFJYSZSeSDh8mVGvugi0exnSJrrBZDyVCcAEQEAAcLB ZQQYAQIADwIbDAUCWZR1ZwUJA59cIQAKCRD5M+tD3xNhH5b+D/9XG44Ci6STdcA5RO/ur05J EE3Ux1DCHZ5V7vNAtX/8Wg4l4GZfweauXwuJ1w7Sp7fklwcNC6wsceI+EmNjGMqfIaukGetG +jBGqsQ7moOZodfXUoCK98gblKgt/BPYMVidzlGC8Q/+lZg1+o29sPnwImW+MXt/Z5az/Z17 Qc265g+p5cqJHzq6bpQdnF7Fu6btKU/kv6wJghENvgMXBuyThqsyFReJWFh2wfaKyuix3Zyj ccq7/blkhzIKmtFWgDcgaSc2UAuJU+x9nuYjihW6WobpKP/nlUDu3BIsbIq09UEke+uE/QK+ FJ8PTJkAsXOf1Bc2C0XbW4Y2hf103+YY6L8weUCBsWC5VH5VtVmeuh26ENURclwfeXhWQ9Og 77yzpTXWr5g1Z0oLpYpWPv745J4bE7pv+dzxOrFdM1xNkzY2pvXph/A8OjxZNQklDkHQ7PIB Lki5L2F4XkEOddUUQchJwzMqTPsggPDmGjgLZrqgO+s4ECZK5+nLD3HEpAbPa3JLDaScy+90 Nu1lAqPUHSnP3vYZVw85ZYm6UCxHE4VLMnnJsN09ZhsOSVR+GyP5Nyw9rT1V3lcsuH7M5Naa 2Xobn9m7l9bRCD/Ji8kG15eV1WTxx1HXVQGjdUYDI7UwegBNbwMLh17XDy+3sn/6SgcqtECA Q6pZKA2mTQxEKMLBZQQYAQIADwIbDAUCWZR3hQUJA59eRwAKCRD5M+tD3xNhH4a/D/4jLAZu UhvU1swWcNEVVCELZ0D3LOV14XcY2MXa3QOpeZ9Bgq7YYJ4S5YXK+SBQS0FkRZdjGNvlGZoG ZdpU+NsQmQFhqHGwX0IT9MeTFM8uvKgxNKGwMVcV9g0IOqwBhGHne+BFboRA9362fgGW5AYQ zT0mzzRKEoOh4r3AQvbM6kLISxo0k1ujdYiI5nj/5WoKDqxTwwfuN1uDUHsWo3tzenRmpMyU NyW3Dc+1ajvXLyo09sRRq7BnM99Rix1EGL8Qhwy+j0YAv+FuspWxUX9FxXYho5PvGLHLsHfK FYQ7x/RRbpMjkJWVfIe/xVnfvn4kz+MTA5yhvsuNi678fLwY9hBP0y4lO8Ob2IhEPdfnTuIs tFVxXuelJ9xAe5TyqP0f+fQjf1ixsBZkqOohsBXDfje0iaUpYa/OQ/BBeej0dUdg2JEu4jAC x41HpVCnP9ipLpD0fYz1d/dX0F/VY2ovW6Eba/y/ngOSAR6C+u881m7oH2l0G47MTwkaQCBA bLGXPj4TCdX3lftqt4bcBPBJ+rFAnJmRHtUuyyaewBnZ81ZU2YAptqFM1kTh+aSvMvGhfVsQ qZL2rk2OPN1hg+KXhErlbTZ6oPtLCFhSHQmuxQ4oc4U147wBTUuOdwNjtnNatUhRCp8POc+3 XphVR5G70mnca1E2vzC77z+XSlTyRA== Message-ID: <5debc6df-9bed-597a-03e2-510372b849e0@intel.com> Date: Thu, 9 Aug 2018 12:30:57 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1533810233-7706-1-git-send-email-kkokkilagadda@caviumnetworks.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [dpdk-dev] [PATCH] kni: fix kni rx fifo producer synchronization X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 09 Aug 2018 11:31:03 -0000 On 8/9/2018 11:23 AM, Kiran Kumar wrote: > With existing code in kni_fifo_put, rx_q values are not being updated > before updating fifo_write. While reading rx_q in kni_net_rx_normal, > This is causing the sync issue on other core. So adding a write > barrier to make sure the values being synced before updating fifo_write. > > Fixes: 3fc5ca2f6352 ("kni: initial import") > > Signed-off-by: Kiran Kumar > --- > lib/librte_kni/rte_kni_fifo.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/lib/librte_kni/rte_kni_fifo.h b/lib/librte_kni/rte_kni_fifo.h > index ac26a8c..4d6b33e 100644 > --- a/lib/librte_kni/rte_kni_fifo.h > +++ b/lib/librte_kni/rte_kni_fifo.h > @@ -39,6 +39,7 @@ kni_fifo_put(struct rte_kni_fifo *fifo, void **data, unsigned num) > fifo->buffer[fifo_write] = data[i]; > fifo_write = new_write; > } > + rte_smp_wmb(); > fifo->write = fifo_write; > return i; For Intel this is just a compiler barrier so no issue but not sure if a memory barrier is required here, Related code block is: |- for (i = 0; i < num; i++) { || new_write = (new_write + 1) & (fifo->len - 1); || || if (new_write == fifo_read) || break; || fifo->buffer[fifo_write] = data[i]; || fifo_write = new_write; || } | fifo->write = fifo_write; "fifo_write" is updated in the loop, so there is a dependency to it for "fifo->write". Can memory writes be reordered when there is a dependency? Cc'ed a few more people for comment.