Re: [PATCH] power: use hugepage memory for queue list entry structure

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 20 Feb 2025 16:39:52 +0000
Konstantin Ananyev <konstantin.ananyev@huawei.com> wrote:

> > -----Original Message-----
> > From: Stephen Hemminger <stephen@networkplumber.org>
> > Sent: Thursday, February 20, 2025 4:12 PM
> > To: lihuisong (C) <lihuisong@huawei.com>
> > Cc: dev@dpdk.org; thomas@monjalon.net; david.hunt@intel.com; anatoly.burakov@intel.com; sivaprasad.tummala@amd.com;
> > liuyonglong <liuyonglong@huawei.com>
> > Subject: Re: [PATCH] power: use hugepage memory for queue list entry structure
> > 
> > On Thu, 20 Feb 2025 17:01:53 +0800
> > "lihuisong (C)" <lihuisong@huawei.com> wrote:
> >   
> > > > The queue_list_entry structure data is used in rx_callback of io path
> > > > when enable PMD Power Management. However its memory is currently from
> > > > normal heap memory. For better performance, use hugepage memory to
> > > > replace it.
> > > >
> > > > Signed-off-by: Huisong Li <lihuisong@huawei.com>  
> > 
> > How is that in a hot path where this could matter?  
> 
> AFAIU - it is used in RX/TX callbacks that power library installs,
> so I presume will get hit on every eth_rx_burst/tx_burst calls.
> 
> > The safety rails in rte_malloc() are much less than regular malloc().
> > I prefer some degree of safety from checkers and malloc library internals.  
> 
> Didn't get your point - what's suddenly wrong with rte_malloc()?

Coverity and Gcc analyzer treat malloc as special case.
With attributes rte_malloc gets similar treatment but not quite as much.
Also internally, malloc and free have more heap pool sanity checks.
In name of performance, those don't exist in rte_malloc().
Lastly hugepages are limited resource, so they should only be used when needed.