From: Thomas Monjalon <thomas@monjalon.net> To: Jerin Jacob <jerinjacobk@gmail.com> Cc: dpdk-dev <dev@dpdk.org>, David Marchand <david.marchand@redhat.com>, Ferruh Yigit <ferruh.yigit@intel.com>, Olivier Matz <olivier.matz@6wind.com>, Morten Brørup <mb@smartsharesystems.com>, "Ananyev, Konstantin" <konstantin.ananyev@intel.com>, Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>, Viacheslav Ovsiienko <viacheslavo@nvidia.com>, Ajit Khaparde <ajit.khaparde@broadcom.com>, Jerin Jacob <jerinj@marvell.com>, Hemant Agrawal <hemant.agrawal@nxp.com>, Ray Kinsella <mdr@ashroe.eu>, Neil Horman <nhorman@tuxdriver.com>, Nithin Dabilpuram <ndabilpuram@marvell.com>, Kiran Kumar K <kirankumark@marvell.com> Subject: Re: [dpdk-dev] [PATCH 1/1] mbuf: move pool pointer in first half Date: Mon, 09 Nov 2020 09:04:08 +0100 Message-ID: <7853350.9sPKUjbg19@thomas> (raw) In-Reply-To: <CALBAE1NN=iF7+V5xSSCrepddmxpuyr8pqZfiZcvpg1XAo8+TJg@mail.gmail.com> 09/11/2020 06:18, Jerin Jacob: > On Sun, Nov 8, 2020 at 2:03 AM Thomas Monjalon <thomas@monjalon.net> wrote: > > 07/11/2020 20:05, Jerin Jacob: > > > On Sun, Nov 8, 2020 at 12:09 AM Thomas Monjalon <thomas@monjalon.net> wrote: > > > > 07/11/2020 18:12, Jerin Jacob: > > > > > On Sat, Nov 7, 2020 at 10:04 PM Thomas Monjalon <thomas@monjalon.net> wrote: > > > > > > > > > > > > The mempool pointer in the mbuf struct is moved > > > > > > from the second to the first half. > > > > > > It should increase performance on most systems having 64-byte cache line, > > > > > > > > > > > i.e. mbuf is split in two cache lines. > > > > > > > > > > But In any event, Tx needs to touch the pool to freeing back to the > > > > > pool upon Tx completion. Right? > > > > > Not able to understand the motivation for moving it to the first 64B cache line? > > > > > The gain varies from driver to driver. For example, a Typical > > > > > ARM-based NPU does not need to > > > > > touch the pool in Rx and its been filled by HW. Whereas it needs to > > > > > touch in Tx if the reference count is implemented. > > > > > > See below. > > > > > > > > > > > > > > Due to this change, tx_offload is moved, so some vector data paths > > > > > > may need to be adjusted. Note: OCTEON TX2 check is removed temporarily! > > > > > > > > > > It will be breaking the Tx path, Please just don't remove the static > > > > > assert without adjusting the code. > > > > > > > > Of course not. > > > > I looked at the vector Tx path of OCTEON TX2, > > > > it's close to be impossible to understand :) > > > > Please help! > > > > > > Off course. Could you check the above section any share the rationale > > > for this change > > > and where it helps and how much it helps? > > > > It has been concluded in the techboard meeting you were part of. > > I don't understand why we restart this discussion again. > > I won't have the energy to restart this process myself. > > If you don't want to apply the techboard decision, then please > > do the necessary to request another quick decision. > > Yes. Initially, I thought it is OK as we have 128B CL, After looking > into Thomas's change, I realized > it is not good for ARM64 64B catchlines based NPU as > - A Typical ARM-based NPU does not need to touch the pool in Rx and > its been filled by HW. Whereas it needs to > touch in Tx if the reference count is implemented. Small note: It is not true for all Arm platforms. > - Also it will be effecting exiting vector routines > > I request to reconsider the tech board decision.
next prev parent reply other threads:[~2020-11-09 8:04 UTC|newest] Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-11-07 15:53 Thomas Monjalon 2020-11-07 17:12 ` Jerin Jacob 2020-11-07 18:39 ` Thomas Monjalon 2020-11-07 19:05 ` Jerin Jacob 2020-11-07 20:33 ` Thomas Monjalon 2020-11-09 5:18 ` Jerin Jacob 2020-11-09 8:04 ` Thomas Monjalon [this message] 2020-11-09 8:27 ` Jerin Jacob 2020-11-09 9:47 ` Bruce Richardson 2020-11-09 12:01 ` Jerin Jacob 2020-11-09 12:59 ` Thomas Monjalon 2020-11-09 13:35 ` Jerin Jacob 2020-11-09 14:02 ` Thomas Monjalon 2020-11-09 14:08 ` Jerin Jacob 2020-11-09 14:42 ` Thomas Monjalon 2020-11-09 14:53 ` Jerin Jacob 2020-11-09 8:16 ` Morten Brørup 2020-11-09 10:06 ` [dpdk-dev] [dpdk-techboard] " Bruce Richardson 2020-11-09 10:21 ` Morten Brørup 2020-11-09 18:04 ` Stephen Hemminger 2020-11-10 7:15 ` Morten Brørup 2020-11-07 18:57 ` [dpdk-dev] " Morten Brørup 2020-11-09 10:08 ` Bruce Richardson 2020-11-09 10:30 ` Morten Brørup 2020-11-09 10:33 ` Ananyev, Konstantin 2020-11-09 10:36 ` Bruce Richardson 2020-11-09 11:24 ` Ananyev, Konstantin 2020-11-09 21:29 ` [dpdk-dev] [PATCH v2 0/2] move mbuf pool pointer Thomas Monjalon 2020-11-09 21:29 ` [dpdk-dev] [PATCH v2 1/2] drivers: disable OCTEON TX2 in 32-bit build Thomas Monjalon 2020-11-10 18:05 ` Jerin Jacob 2020-11-09 21:29 ` [dpdk-dev] [PATCH v2 2/2] mbuf: move pool pointer in first half Thomas Monjalon 2020-11-10 10:05 ` Morten Brørup 2020-11-10 10:44 ` Thomas Monjalon 2020-11-10 16:25 ` Olivier Matz 2020-11-10 18:06 ` Jerin Jacob 2020-11-12 14:39 ` Thomas Monjalon 2020-11-10 18:08 ` Stephen Hemminger
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