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From: "Liu, Yong" <yong.liu@intel.com>
To: Thomas Monjalon <thomas@monjalon.net>
Cc: "Richardson, Bruce" <bruce.richardson@intel.com>,
	"stephen@networkplumber.org" <stephen@networkplumber.org>,
	"dev@dpdk.org" <dev@dpdk.org>,
	"david.marchand@redhat.com" <david.marchand@redhat.com>,
	"Yigit, Ferruh" <ferruh.yigit@intel.com>,
	"maxime.coquelin@redhat.com" <maxime.coquelin@redhat.com>,
	"honnappa.nagarahalli@arm.com" <honnappa.nagarahalli@arm.com>,
	David Christensen <drc@linux.vnet.ibm.com>,
	"ruifeng.wang@arm.com" <ruifeng.wang@arm.com>
Subject: Re: [dpdk-dev] [PATCH v2] config: enable packet data prefetch
Date: Thu, 15 Oct 2020 01:21:22 +0000
Message-ID: <94797350feac4f3cbfce7223e95e3add@intel.com> (raw)
In-Reply-To: <3900730.QmOVHUWFXi@thomas>



> -----Original Message-----
> From: Thomas Monjalon <thomas@monjalon.net>
> Sent: Thursday, October 15, 2020 6:03 AM
> To: Liu, Yong <yong.liu@intel.com>
> Cc: Richardson, Bruce <bruce.richardson@intel.com>;
> stephen@networkplumber.org; dev@dpdk.org;
> david.marchand@redhat.com; Yigit, Ferruh <ferruh.yigit@intel.com>;
> maxime.coquelin@redhat.com; honnappa.nagarahalli@arm.com; David
> Christensen <drc@linux.vnet.ibm.com>; ruifeng.wang@arm.com
> Subject: Re: [dpdk-dev] [PATCH v2] config: enable packet data prefetch
> 
> 23/09/2020 03:51, Marvin Liu:
> > Data prefetch instruction can preload data into cpu’s hierarchical
> > cache before data access. Virtualized data paths like virtio utilized
> > this feature for acceleration. Since most modern cpus have support
> > prefetch function, we can enable packet data prefetch as default.
> >
> > Signed-off-by: Marvin Liu <yong.liu@intel.com>
> > ---
> > +#define RTE_PMD_PACKET_PREFETCH 1
> 
> We could also remove the related #ifdefs.
> 
> What can be the drawback of always enable those prefetches?
> 

Hi Thomas,
I think the potential drawback is that current prefetch location cannot guarantee the best performance across different platforms. 
Each developer has tuned the performance by adding prefetch instruction and verified the result on himself platform. 
So prefetch location is based on certain platform, also it will be hard for developer to compare the results across platforms. 

Thanks,
Marvin

  reply	other threads:[~2020-10-15  1:21 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-22  8:21 [dpdk-dev] [PATCH] build: " Marvin Liu
2020-09-22 14:11 ` Stephen Hemminger
2020-09-23  2:00   ` Liu, Yong
2020-09-23  1:51 ` [dpdk-dev] [PATCH v2] config: " Marvin Liu
2020-10-14 22:02   ` Thomas Monjalon
2020-10-15  1:21     ` Liu, Yong [this message]
2020-10-15  4:09       ` Honnappa Nagarahalli
2020-10-15  8:23         ` Liu, Yong
2020-10-15  9:21           ` Thomas Monjalon
2020-10-15 14:38             ` Honnappa Nagarahalli
2020-11-03  1:57   ` [dpdk-dev] [PATCH v3] drivers/net: enable packet data prefetch on x86 Marvin Liu

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