Re: [dpdk-dev] [dpdk-stable] [PATCH v2 2/4] hash: add local cache for TSX region

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, Nov 13, 2018 at 05:24:55PM +0000, Wang, Yipeng1 wrote:
> >-----Original Message-----
> >From: Honnappa Nagarahalli [mailto:Honnappa.Nagarahalli@arm.com]
> >Sent: Tuesday, November 13, 2018 9:17 AM
> >To: Thomas Monjalon <thomas@monjalon.net>; Richardson, Bruce <bruce.richardson@intel.com>; Wang, Yipeng1
> ><yipeng1.wang@intel.com>
> >Cc: stable@dpdk.org; dev@dpdk.org; nd <nd@arm.com>; nd <nd@arm.com>
> >Subject: RE: [dpdk-stable] [dpdk-dev] [PATCH v2 2/4] hash: add local cache for TSX region
> >> > >  	/* Check extra flags field to check extra options. */
> >> > > -	if (params->extra_flag &
> >> > > RTE_HASH_EXTRA_FLAGS_TRANS_MEM_SUPPORT)
> >> > > +	if (params->extra_flag &
> >> > > RTE_HASH_EXTRA_FLAGS_TRANS_MEM_SUPPORT) {
> >> > > +		use_local_cache = 1;
> >> > Do you see the issue even in the case of single writer? Enabling this flag
> >> creates local caches on all the data plane cores. This increases the memory
> >> usage for the single writer use case. Then there is 'writers on the control
> >> plane' use case, the requirement on hash_add rate is comparatively lower
> >> when compared to 'writers on the data plane'. The writers also are not pinned
> >> to any core as well. In this use case, I am not sure how much having a local
> >> cache matters.
> >> >
> >> > Enabling this flag effectively changes the free slot allocation from a ring to a
> >> stack data structure. Does it indicate that for single writer use case with TSX,
> >> the free slot (global) data structure should be a stack (rather than a ring)?
> >>
> >> Is it blocking this patchset from entering in 18.11?
> >> If I understand well, there are some fixes for 18.11.
> 
> [Wang, Yipeng] Hi Thomas, please go ahead merge the other commits without this one since Honnapa's concern.
> I will talk with Honnappa separately on a better way to do this.
> 
> Thanks!

No objections to that plan here.

/Bruce