[PATCH v8] mempool: improve cache behaviour and performance

[Wisam Jaddo]

Hi,

Thank you for your guidance, the rates are back to normal. After the new configuration.

BRs,
Wisam Jaddo


> -----Original Message-----
> From: Morten Brørup <mb at smartsharesystems.com>
> Sent: Wednesday, July 8, 2026 7:25 PM
> To: Wisam Jaddo <wisamm at nvidia.com>; NBU-Contact-Thomas Monjalon
> (EXTERNAL) <thomas at monjalon.net>; Andrew Rybchenko
> <andrew.rybchenko at oktetlabs.ru>
> Cc: dev at dpdk.org; Raslan Darawsheh <rasland at nvidia.com>; Maayan
> Kashani <mkashani at nvidia.com>
> Subject: RE: [PATCH v8] mempool: improve cache behaviour and performance
> 
> > From: Wisam Jaddo [mailto:wisamm at nvidia.com]
> > Sent: Wednesday, 8 July 2026 17.05
> >
> > Hi,
> >
> > Tested on ARM BF3:
> > command:
> > . /dpdk-testpmd -n 4  -a 0000:03:00.0,dv_flow_en=2  -a
> > 0000:03:00.1,dv_flow_en=2  -a auxiliary:  -a 00:00.0 -c 0x30  -- --
> > mbcache=512 -i  --nb-cores=1  --burst=64 --txd=256 --rxd=256
> > --record- burst-stats --record-core-cycles --auto-start
> 
> Thank you for the detailed response.
> 
> As noted in the release notes with the patch, the effective mempool cache size
> was changed to no longer be 1.5 times the configured cache size. (This change
> fixed bug 1027 [BZ1027].) I.e. with your testpmd parameters the effective
> mbuf mempool cache size was reduced from 768 (1.5 * 512) to 512 mbufs.
> In order to test with the same effective mbuf mempool cache size, you need to
> pass --mbcache=768.
> And since 768 exceeds RTE_MEMPOOL_CACHE_MAX_SIZE (default 512) in
> rte_config.h, you also need to rebuild DPDK with that set to 1024 instead of
> 512.
> 
> [BZ1027] https://bugs.dpdk.org/show_bug.cgi?id=1027
> 
> Please let us know your updated test results, if you decide to retest with --
> mbcache=768 and DPDK rebuilt with RTE_MEMPOOL_CACHE_MAX_SIZE
> 1024.
> 
> >
> > No offloads, plain testpmd with auto-start.
> > On the other end I have ixia generating the ipv4_udp traffic, with
> > dest udp range from 65024 to 65280 "To send different packets with msg
> > size 64Bytes.
> >
> > We send 100% on TX side, and we read what we reactive back on RX side
> > in ixia "using two ports agg."
> > The results that we start to see after this commit is a degradation of
> > 1.8% - 2%
> >
> > BRs,
> > Wisam Jaddo
> >
> > > -----Original Message-----
> > > From: Morten Brørup <mb at smartsharesystems.com>
> > > Sent: Wednesday, July 8, 2026 5:09 PM
> > > To: Wisam Jaddo <wisamm at nvidia.com>; NBU-Contact-Thomas Monjalon
> > > (EXTERNAL) <thomas at monjalon.net>
> > > Cc: dev at dpdk.org; Andrew Rybchenko
> <andrew.rybchenko at oktetlabs.ru>;
> > > Raslan Darawsheh <rasland at nvidia.com>; Maayan Kashani
> > > <mkashani at nvidia.com>
> > > Subject: RE: [PATCH v8] mempool: improve cache behaviour and
> > performance
> > >
> > > > From: Wisam Jaddo [mailto:wisamm at nvidia.com]
> > > > Sent: Wednesday, 8 July 2026 14.28
> > > >
> > > > Hi,
> > > >
> > > > Our internal performance testing are showing degradation starting
> > from
> > > > this commit.
> > > > The degradation is about 1.8% - 2% on small msg szies.
> > >
> > > What do you mean "small message sizes"?
> > >
> > > Also, please share more details about the test case:
> > > Access pattern, e.g. pipelined across multiple threads or run-to-
> > completion? If
> > > possible, link to test case source code?
> > > Get and put burst sizes?
> > > Mempool cache size?
> > > Mempool driver?
> > >
> > > PS: I assume it is about mbuf mempool. Or is it some other object
> > type in the
> > > mempool?
> > >
> > > >
> > > > BRs,
> > > > Wisam Jaddo
> > > >
> > > > > -----Original Message-----
> > > > > From: Thomas Monjalon <thomas at monjalon.net>
> > > > > Sent: Wednesday, June 10, 2026 2:07 PM
> > > > > To: Morten Brørup <mb at smartsharesystems.com>
> > > > > Cc: dev at dpdk.org; Andrew Rybchenko
> > <andrew.rybchenko at oktetlabs.ru>
> > > > > Subject: Re: [PATCH v8] mempool: improve cache behaviour and
> > > > performance
> > > > >
> > > > > 04/06/2026 13:48, Morten Brørup:
> > > > > > This patch refactors the mempool cache to eliminate some
> > > > > > unexpected behaviour and reduce the mempool cache miss rate.
> > > > >
> > > > > Applied, thanks.
> > > > >
> > > > >