From: Christoph Hellwig <hch@lst.de> To: Sagi Grimberg <sagi@grimberg.me> Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>, Keith Busch <keith.busch@intel.com>, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org Subject: Re: [PATCH 08/10] block: provide a generic_make_request_fast helper Date: Mon, 28 Aug 2017 10:54:47 +0200 [thread overview] Message-ID: <20170828085447.GB4358@lst.de> (raw) In-Reply-To: <326ee3b3-441f-e093-6d6f-7356e1ff8487@grimberg.me> On Mon, Aug 28, 2017 at 10:00:35AM +0300, Sagi Grimberg wrote: >> This helper allows reinserting a bio into a new queue without much >> overhead, but requires all queue limits to be the same for the upper >> and lower queues, and it does not provide any recursion preventions, >> which requires the caller to not split the bio. > > Isn't the same limits constraint too restrictive? > > Say I have two paths to the same namespace via two different HBAs, each > with its own virt_boundary capability for example? That would require us > to split failover bio wouldn't it? Uh oh - different transports for the same subsystem will be intereting. For one it's not specified anywhere so I'd like to kick off a discussion on the working group mailing list about it. That being said ->make_request basically doesn't care about actual limits at all, it mostly care about support features (e.g. discard, fua, etc). So I think a lot of these limits could porbably be lifted, but I'd need to add the check to generic_make_request_checks back. >> +/* >> + * Fast-path version of generic_make_request. > > generic_make_request is also called in the fast-path, maybe reword it > to: "Fast version of generic_make_request" Yeah. Maybe generic_make_request_direct or direct_make_request is a better name as it describes the recursion avoidance bypassing a little better.
WARNING: multiple messages have this Message-ID (diff)
From: hch@lst.de (Christoph Hellwig) Subject: [PATCH 08/10] block: provide a generic_make_request_fast helper Date: Mon, 28 Aug 2017 10:54:47 +0200 [thread overview] Message-ID: <20170828085447.GB4358@lst.de> (raw) In-Reply-To: <326ee3b3-441f-e093-6d6f-7356e1ff8487@grimberg.me> On Mon, Aug 28, 2017@10:00:35AM +0300, Sagi Grimberg wrote: >> This helper allows reinserting a bio into a new queue without much >> overhead, but requires all queue limits to be the same for the upper >> and lower queues, and it does not provide any recursion preventions, >> which requires the caller to not split the bio. > > Isn't the same limits constraint too restrictive? > > Say I have two paths to the same namespace via two different HBAs, each > with its own virt_boundary capability for example? That would require us > to split failover bio wouldn't it? Uh oh - different transports for the same subsystem will be intereting. For one it's not specified anywhere so I'd like to kick off a discussion on the working group mailing list about it. That being said ->make_request basically doesn't care about actual limits at all, it mostly care about support features (e.g. discard, fua, etc). So I think a lot of these limits could porbably be lifted, but I'd need to add the check to generic_make_request_checks back. >> +/* >> + * Fast-path version of generic_make_request. > > generic_make_request is also called in the fast-path, maybe reword it > to: "Fast version of generic_make_request" Yeah. Maybe generic_make_request_direct or direct_make_request is a better name as it describes the recursion avoidance bypassing a little better.
next prev parent reply other threads:[~2017-08-28 8:54 UTC|newest] Thread overview: 122+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-08-23 17:58 RFC: nvme multipath support Christoph Hellwig 2017-08-23 17:58 ` Christoph Hellwig 2017-08-23 17:58 ` [PATCH 01/10] nvme: report more detailed status codes to the block layer Christoph Hellwig 2017-08-23 17:58 ` Christoph Hellwig 2017-08-28 6:06 ` Sagi Grimberg 2017-08-28 6:06 ` Sagi Grimberg 2017-08-28 18:50 ` Keith Busch 2017-08-28 18:50 ` Keith Busch 2017-08-23 17:58 ` [PATCH 02/10] nvme: allow calling nvme_change_ctrl_state from irq context Christoph Hellwig 2017-08-23 17:58 ` Christoph Hellwig 2017-08-28 6:06 ` Sagi Grimberg 2017-08-28 6:06 ` Sagi Grimberg 2017-08-28 18:50 ` Keith Busch 2017-08-28 18:50 ` Keith Busch 2017-08-23 17:58 ` [PATCH 03/10] nvme: remove unused struct nvme_ns fields Christoph Hellwig 2017-08-23 17:58 ` Christoph Hellwig 2017-08-28 6:07 ` Sagi Grimberg 2017-08-28 6:07 ` Sagi Grimberg 2017-08-28 19:13 ` Keith Busch 2017-08-28 19:13 ` Keith Busch 2017-08-23 17:58 ` [PATCH 04/10] nvme: remove nvme_revalidate_ns Christoph Hellwig 2017-08-23 17:58 ` Christoph Hellwig 2017-08-28 6:12 ` Sagi Grimberg 2017-08-28 6:12 ` Sagi Grimberg 2017-08-28 19:14 ` Keith Busch 2017-08-28 19:14 ` Keith Busch 2017-08-23 17:58 ` [PATCH 05/10] nvme: don't blindly overwrite identifiers on disk revalidate Christoph Hellwig 2017-08-23 17:58 ` Christoph Hellwig 2017-08-28 6:17 ` Sagi Grimberg 2017-08-28 6:17 ` Sagi Grimberg 2017-08-28 6:23 ` Christoph Hellwig 2017-08-28 6:23 ` Christoph Hellwig 2017-08-28 6:32 ` Sagi Grimberg 2017-08-28 6:32 ` Sagi Grimberg 2017-08-28 19:15 ` Keith Busch 2017-08-28 19:15 ` Keith Busch 2017-08-23 17:58 ` [PATCH 06/10] nvme: track subsystems Christoph Hellwig 2017-08-23 17:58 ` Christoph Hellwig 2017-08-23 22:04 ` Keith Busch 2017-08-23 22:04 ` Keith Busch 2017-08-24 8:52 ` Christoph Hellwig 2017-08-24 8:52 ` Christoph Hellwig 2017-08-28 6:22 ` Sagi Grimberg 2017-08-28 6:22 ` Sagi Grimberg 2017-08-23 17:58 ` [PATCH 07/10] nvme: track shared namespaces Christoph Hellwig 2017-08-23 17:58 ` Christoph Hellwig 2017-08-28 6:51 ` Sagi Grimberg 2017-08-28 6:51 ` Sagi Grimberg 2017-08-28 8:50 ` Christoph Hellwig 2017-08-28 8:50 ` Christoph Hellwig 2017-08-28 20:21 ` J Freyensee 2017-08-28 20:21 ` J Freyensee 2017-08-29 8:25 ` Christoph Hellwig 2017-08-29 8:25 ` Christoph Hellwig 2017-08-29 6:54 ` Guan Junxiong 2017-08-29 6:54 ` Guan Junxiong 2017-08-28 12:04 ` javigon 2017-08-28 12:04 ` javigon 2017-08-28 12:41 ` Guan Junxiong 2017-08-28 12:41 ` Guan Junxiong 2017-08-28 14:30 ` Christoph Hellwig 2017-08-28 14:30 ` Christoph Hellwig 2017-08-29 2:42 ` Guan Junxiong 2017-08-29 2:42 ` Guan Junxiong 2017-08-29 8:30 ` Christoph Hellwig 2017-08-29 8:30 ` Christoph Hellwig 2017-08-29 8:29 ` Christoph Hellwig 2017-08-29 8:29 ` Christoph Hellwig 2017-08-28 19:18 ` Keith Busch 2017-08-28 19:18 ` Keith Busch 2017-08-23 17:58 ` [PATCH 08/10] block: provide a generic_make_request_fast helper Christoph Hellwig 2017-08-23 17:58 ` Christoph Hellwig 2017-08-28 7:00 ` Sagi Grimberg 2017-08-28 7:00 ` Sagi Grimberg 2017-08-28 8:54 ` Christoph Hellwig [this message] 2017-08-28 8:54 ` Christoph Hellwig 2017-08-28 11:01 ` Sagi Grimberg 2017-08-28 11:01 ` Sagi Grimberg 2017-08-28 11:54 ` Christoph Hellwig 2017-08-28 11:54 ` Christoph Hellwig 2017-08-28 12:38 ` Sagi Grimberg 2017-08-28 12:38 ` Sagi Grimberg 2017-08-23 17:58 ` [PATCH 09/10] blk-mq: add a blk_steal_bios helper Christoph Hellwig 2017-08-23 17:58 ` Christoph Hellwig 2017-08-28 7:04 ` Sagi Grimberg 2017-08-28 7:04 ` Sagi Grimberg 2017-08-23 17:58 ` [PATCH 10/10] nvme: implement multipath access to nvme subsystems Christoph Hellwig 2017-08-23 17:58 ` Christoph Hellwig 2017-08-23 18:21 ` Bart Van Assche 2017-08-23 18:21 ` Bart Van Assche 2017-08-24 8:59 ` hch 2017-08-24 8:59 ` hch 2017-08-24 20:17 ` Bart Van Assche 2017-08-24 20:17 ` Bart Van Assche 2017-09-05 11:53 ` Christoph Hellwig 2017-09-05 11:53 ` Christoph Hellwig 2017-09-11 6:34 ` Tony Yang 2017-08-23 22:53 ` Keith Busch 2017-08-23 22:53 ` Keith Busch 2017-08-24 8:52 ` Christoph Hellwig 2017-08-24 8:52 ` Christoph Hellwig 2017-08-28 7:23 ` Sagi Grimberg 2017-08-28 7:23 ` Sagi Grimberg 2017-08-28 9:06 ` Christoph Hellwig 2017-08-28 9:06 ` Christoph Hellwig 2017-08-28 13:40 ` Sagi Grimberg 2017-08-28 13:40 ` Sagi Grimberg 2017-08-28 14:24 ` Christoph Hellwig 2017-08-28 14:24 ` Christoph Hellwig 2017-09-07 15:17 ` Tony Yang 2017-08-29 10:22 ` Guan Junxiong 2017-08-29 10:22 ` Guan Junxiong 2017-08-29 14:51 ` Christoph Hellwig 2017-08-29 14:51 ` Christoph Hellwig 2017-08-29 14:54 ` Keith Busch 2017-08-29 14:54 ` Keith Busch 2017-08-29 14:55 ` Christoph Hellwig 2017-08-29 14:55 ` Christoph Hellwig 2017-08-29 15:41 ` Keith Busch 2017-08-29 15:41 ` Keith Busch 2017-09-18 0:17 ` Christoph Hellwig 2017-09-18 0:17 ` Christoph Hellwig
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