linux-kernel - Re: [PATCH 2/9] IB: add a proper completion queue abstraction

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 15 Nov 2015 13:55:01 +0100
From:	Christoph Hellwig <hch@....de>
To:	Sagi Grimberg <sagig@....mellanox.co.il>
Cc:	Christoph Hellwig <hch@....de>, linux-rdma@...r.kernel.org,
	bart.vanassche@...disk.com, axboe@...com,
	linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/9] IB: add a proper completion queue abstraction

On Sun, Nov 15, 2015 at 11:40:02AM +0200, Sagi Grimberg wrote:
> I doubt INT_MAX is useful as a budget in any use-case. it can easily
> hog the CPU. If the consumer is given access to poll a CQ, it must be
> able to provide some way to budget it. Why not expose a budget argument
> to the consumer?

Because in theory we could have a lot of sends completing before
we finally need to reap them.  I think that's more of a theoretical
than real issue.

My preference would be to simply kill this mode though.  Allocate a IU
to each block request in SRP and only use the free_tx list for task
management and AEN/req_limit calls.  Then we can use a single CQ
and mark the regular I/O requests as unsignalled.

AFAICS no other driver wants a similar polling mode as the SRP initiator
does for it's send queue.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/