From: Sagi Grimberg <sagi@grimberg.me>
To: Hannes Reinecke <hare@suse.de>, Keith Busch <kbusch@kernel.org>
Cc: "Ewan D. Milne" <emilne@redhat.com>,
Daniel Wagner <dwagner@suse.de>,
linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
Jens Axboe <axboe@fb.com>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v2] nvme-tcp: Check if request has started before processing it
Date: Tue, 11 May 2021 11:16:10 -0700 [thread overview]
Message-ID: <1989b8fe-7ef2-2145-75c5-5e938f74014c@grimberg.me> (raw)
In-Reply-To: <8a396f94-ac33-6bea-8d70-ded0188eb98a@suse.de>
On 5/9/21 4:30 AM, Hannes Reinecke wrote:
> On 5/8/21 1:22 AM, Sagi Grimberg wrote:
>>
>>>>> Well, that would require a modification to the CQE specification, no?
>>>>> fmds was not amused when I proposed that :-(
>>>>
>>>> Why would that require a modification to the CQE? it's just using say
>>>> 4 msbits of the command_id to a running sequence...
>>>
>>> I think Hannes was under the impression that the counter proposal wasn't
>>> part of the "command_id". The host can encode whatever it wants in that
>>> value, and the controller just has to return the same value.
>>
>> Yea, maybe something like this?
>> --
>> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>> index e6612971f4eb..7af48827ea56 100644
>> --- a/drivers/nvme/host/core.c
>> +++ b/drivers/nvme/host/core.c
>> @@ -1006,7 +1006,7 @@ blk_status_t nvme_setup_cmd(struct nvme_ns *ns,
>> struct request *req)
>> return BLK_STS_IOERR;
>> }
>>
>> - cmd->common.command_id = req->tag;
>> + cmd->common.command_id = nvme_cid(req);
>> trace_nvme_setup_cmd(req, cmd);
>> return ret;
>> }
>> diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
>> index 05f31a2c64bb..96abfb0e2ddd 100644
>> --- a/drivers/nvme/host/nvme.h
>> +++ b/drivers/nvme/host/nvme.h
>> @@ -158,6 +158,7 @@ enum nvme_quirks {
>> struct nvme_request {
>> struct nvme_command *cmd;
>> union nvme_result result;
>> + u8 genctr;
>> u8 retries;
>> u8 flags;
>> u16 status;
>> @@ -497,6 +498,48 @@ struct nvme_ctrl_ops {
>> int (*get_address)(struct nvme_ctrl *ctrl, char *buf, int size);
>> };
>>
>> +/*
>> + * nvme command_id is constructed as such:
>> + * | xxxx | xxxxxxxxxxxx |
>> + * gen request tag
>> + */
>> +#define nvme_cid_install_genctr(gen) ((gen & 0xf) << 12)
>> +#define nvme_genctr_from_cid(cid) ((cid & 0xf000) >> 12)
>> +#define nvme_tag_from_cid(cid) (cid & 0xfff)
>> +
>
> That is a good idea, but we should ensure to limit the number of
> commands a controller can request, too.
We take the minimum between what the host does vs. what the controller
supports anyways.
> As per spec each controller can support a full 32 bit worth of requests,
> and if we limit that arbitrarily from the stack we'll need to cap the
> number of requests a controller or fabrics driver can request.
NVMF_MAX_QUEUE_SIZE is already 1024, you are right that we also need:
--
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 92e03f15c9f6..66a4a7f7c504 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -60,6 +60,7 @@ MODULE_PARM_DESC(sgl_threshold,
"Use SGLs when average request segment size is larger
or equal to "
"this size. Use 0 to disable SGLs.");
+#define NVME_PCI_MAX_QUEUE_SIZE 4096
static int io_queue_depth_set(const char *val, const struct
kernel_param *kp);
static const struct kernel_param_ops io_queue_depth_ops = {
.set = io_queue_depth_set,
@@ -68,7 +69,7 @@ static const struct kernel_param_ops
io_queue_depth_ops = {
static unsigned int io_queue_depth = 1024;
module_param_cb(io_queue_depth, &io_queue_depth_ops, &io_queue_depth,
0644);
-MODULE_PARM_DESC(io_queue_depth, "set io queue depth, should >= 2");
+MODULE_PARM_DESC(io_queue_depth, "set io queue depth, should >= 2 and
<= 4096");
static int io_queue_count_set(const char *val, const struct
kernel_param *kp)
{
@@ -164,6 +165,9 @@ static int io_queue_depth_set(const char *val, const
struct kernel_param *kp)
if (ret != 0 || n < 2)
return -EINVAL;
+ if (n > NVME_PCI_MAX_QUEUE_SIZE)
+ return -EINVAL;
+
return param_set_uint(val, kp);
}
--
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next prev parent reply other threads:[~2021-05-11 18:16 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-01 17:56 [PATCH v2] nvme-tcp: Check if request has started before processing it Daniel Wagner
2021-03-05 19:57 ` Sagi Grimberg
2021-03-11 9:43 ` Daniel Wagner
2021-03-15 17:16 ` Sagi Grimberg
2021-03-30 16:19 ` Ewan D. Milne
2021-03-30 17:34 ` Sagi Grimberg
2021-03-30 23:28 ` Keith Busch
2021-03-31 7:11 ` Hannes Reinecke
2021-03-31 21:01 ` Ewan D. Milne
2021-03-31 22:24 ` Sagi Grimberg
2021-04-01 6:20 ` Christoph Hellwig
2021-04-01 8:25 ` Sagi Grimberg
2021-03-31 22:37 ` Sagi Grimberg
2021-05-06 15:36 ` Hannes Reinecke
2021-05-07 20:26 ` Sagi Grimberg
2021-05-07 20:40 ` Keith Busch
2021-05-07 23:22 ` Sagi Grimberg
2021-05-08 0:03 ` Keith Busch
2021-05-09 11:30 ` Hannes Reinecke
2021-05-11 18:16 ` Sagi Grimberg [this message]
2021-05-17 14:58 ` Daniel Wagner
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