From: Leon Romanovsky <firstname.lastname@example.org> To: Gal Pressman <email@example.com> Cc: Jason Gunthorpe <firstname.lastname@example.org>, Doug Ledford <email@example.com>, firstname.lastname@example.org, Alexander Matushevsky <email@example.com>, Firas JahJah <firstname.lastname@example.org>, Yossi Leybovich <email@example.com> Subject: Re: [PATCH for-next] RDMA/efa: Move provider specific attributes to ucontext allocation response Date: Tue, 16 Jun 2020 12:38:35 +0300 [thread overview] Message-ID: <20200616093835.GB2383158@unreal> (raw) In-Reply-To: <firstname.lastname@example.org> On Tue, Jun 16, 2020 at 11:53:11AM +0300, Gal Pressman wrote: > On 16/06/2020 9:30, Leon Romanovsky wrote: > > On Mon, Jun 15, 2020 at 10:59:20AM +0300, Gal Pressman wrote: > >> Provider specific attributes which are necessary for the userspace > >> functionality should be part of the alloc ucontext response, not query > >> device. This way a userspace provider could work without issuing a query > >> device verb call. However, the fields will remain in the query device > >> ABI in order to maintain backwards compatibility. > > > > I don't really understand why "should be ..."? Device properties exposed > > here are per-device and will be equal to all ucontexts, so instead of > > doing one very fast system call, you are "punishing" every ucontext > > call. > > I talked about it with Jason in the past, the query device verb is intended to > follow the IBA verb, alloc ucontext should return driver specific data that's > required to operate the user space provider. > A query device call should not be mandatory to load the provider. Why? query_device is declared as mandatory verb for any provider, so anyway all in-the-tree RDMA drivers will have such verb. > > Whether it's done through query device/ucontext response, both happen for each > new context call. With this patch, we gather all needed data in one system call > instead of two. Is it important in control path to have one call? > > > What is wrong with calling one query_device before allocating any > > ucontext? What are you trying to achieve and what will it give? > > How can you call query device without allocating a context? Forget about my comment above, it was my over-thinking. I had in mind some scheme that first ucontext will cache the all device related data and share it with other ucontexts. Thanks
next prev parent reply other threads:[~2020-06-16 10:45 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-06-15 7:59 Gal Pressman 2020-06-16 6:30 ` Leon Romanovsky 2020-06-16 8:53 ` Gal Pressman 2020-06-16 9:38 ` Leon Romanovsky [this message] 2020-06-16 17:44 ` Gal Pressman 2020-06-17 4:55 ` Leon Romanovsky 2020-06-17 15:36 ` Jason Gunthorpe 2020-06-17 17:49 ` Gal Pressman 2020-06-18 11:30 ` Gal Pressman 2020-06-25 10:53 ` Gal Pressman
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