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Thu, 10 Sep 2020 22:04:05 +0000 (GMT) To: Omkar Maslekar , dev@dpdk.org Cc: bruce.richardson@intel.com, ciara.loftus@intel.com References: <1599700614-22809-1-git-send-email-omkar.maslekar@intel.com> <1599700614-22809-2-git-send-email-omkar.maslekar@intel.com> From: David Christensen Message-ID: <4254f439-682a-cdea-89ca-20930d43836b@linux.vnet.ibm.com> Date: Thu, 10 Sep 2020 15:04:04 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <1599700614-22809-2-git-send-email-omkar.maslekar@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-09-10_09:2020-09-10, 2020-09-10 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 lowpriorityscore=0 mlxlogscore=999 spamscore=0 bulkscore=0 clxscore=1011 impostorscore=0 mlxscore=0 suspectscore=0 priorityscore=1501 adultscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009100191 Subject: Re: [dpdk-dev] [PATCH] EAL: An addition of cache line demote (CLDEMOTE) in rte_prefetch.h 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: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 9/9/20 6:16 PM, Omkar Maslekar wrote: > rte_cldemote is similar to a prefetch hint - in reverse. cldemote(addr) > enables software to hint to hardware that line is likely to be shared. > Useful in core-to-core communications where cache-line is likely to be > shared. ARM and PPC implementation is provided with NOP and can be added > if any equivalent instructions could be used for implementation on those > architectures. > > Signed-off-by: Omkar Maslekar > --- ... > diff --git a/lib/librte_eal/ppc/include/rte_prefetch.h b/lib/librte_eal/ppc/include/rte_prefetch.h > index 9ba07c8..3fe9655 100644 > --- a/lib/librte_eal/ppc/include/rte_prefetch.h > +++ b/lib/librte_eal/ppc/include/rte_prefetch.h > @@ -34,6 +34,11 @@ static inline void rte_prefetch_non_temporal(const volatile void *p) > rte_prefetch0(p); > } > > +static inline void rte_cldemote(const volatile void *p) > +{ > + RTE_SET_USED(p); > +} > + > #ifdef __cplusplus > } > #endif For POWER there's an instruction defined in the ISA which is the most similar, miso (i.e. Make It So), but the instruction is interpreted as a NOP in the POWER8/POWER9 CPUs, so NOP is the right choice for PPC at this time. Dave