Re: [RFC] eal: RFC to refactor rte_eal_init into sub-functions

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu,  2 Nov 2023 11:19:24 -0700
Rahul Gupta <rahulgupt@linux.microsoft.com> wrote:

> From: Rahul Gupta <rahulgupt@linux.microsoft.com>
> To: dev@dpdk.org,  thomas@monjalon.net
> Cc: sovaradh@linux.microsoft.com, okaya@kernel.org, sujithsankar@microsoft.com,  sowmini.varadhan@microsoft.com, rahulrgupta27@gmail.com,  Rahul Gupta <rahulgupt@microsoft.com>,  Rahul Gupta <rahulgupt@linux.microsoft.com>
> Subject: [RFC] eal: RFC to refactor rte_eal_init into sub-functions
> Date: Thu,  2 Nov 2023 11:19:24 -0700
> X-Mailer: git-send-email 1.8.3.1
> 
> From: Rahul Gupta <rahulgupt@microsoft.com>
> 
> Initialization often requires rte_eal_init + rte_pktmbuf_pool_create
> which can consume a total time of 500-600 ms:
> a) For many devices FLR may take a significant chunk of time
>    (200-250 ms in our use-case), this FLR is triggered during device
>    probe in rte_eal_init().
> b) rte_pktmbuf_pool_create() can consume upto 300-350 ms for
> applications that require huge memory.
> 
> This cost is incurred on each restart (which happens in our use-case
> during binary updates for servicing).
> This patch provides an optimization using pthreads that appplications
> can use and which can save 200-230ms.
> 
> In this patch, rte_eal_init() is refactored into two parts-
> a) 1st part is dependent code ie- it’s a perquisite of the FLR and
>    mempool creation. So this code needs to be executed before any
>    pthreads. Its named as rte_eal_init_setup()
> b) 2nd part of code is independent code ie- it can execute in parallel
>    to mempool creation in a pthread. Its named as rte_probe_and_ioctl().
> 
> Existing applications require no changes unless they wish to leverage
> the optimization.
> 
> If the application wants to use pthread functionality, it should call-
> a) rte_eal_init_setup() then create two or more pthreads-
> b) in one pthread call- rte_probe_and_ioctl(),
> c) second pthread call- rte_pktmbuf_pool_create()
> d) (optional) Other pthreads for  any other independent function.
> 
> Signed-off-by: Rahul Gupta <rahulgupt@linux.microsoft.com>

These probably marked internal rather than part of API/ABI.