From: Joel Granados <j.granados@samsung.com>
To: Keith Busch <kbusch@kernel.org>
Cc: <sagi@grimberg.me>, <hch@lst.de>,
<linux-nvme@lists.infradead.org>, <gost.dev@samsung.com>,
<joshi.k@samsung.com>, <javier.gonz@samsung.com>,
<p.raghav@samsung.com>
Subject: Re: [RFC 3/3] nvme : Add ioctl to query nvme attributes
Date: Fri, 28 Oct 2022 12:38:27 +0200 [thread overview]
Message-ID: <20221028103827.o7uhl36qavkpx22d@localhost> (raw)
In-Reply-To: <Y1q4Cjg1cv9w+YWR@kbusch-mbp.dhcp.thefacebook.com>
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On Thu, Oct 27, 2022 at 10:55:38AM -0600, Keith Busch wrote:
> On Thu, Oct 27, 2022 at 05:57:24PM +0200, Joel Granados wrote:
> > +{
> > + int ret;
> > + struct nvme_id_ctrl *id_ctrl;
> > + struct nvme_get_attr nvme_get_attr = {0};
> > + struct nvme_id_ctrl_nvm *id_ctrl_nvm;
> > + __u32 usize;
> > +
> > + BUILD_BUG_ON(sizeof(struct nvme_get_attr) < NVME_IOCTL_GET_ATTR_V0SZ);
> > + BUILD_BUG_ON(sizeof(struct nvme_get_attr) != NVME_IOCTL_GET_ATTR_CURSZ);
> > +
> > + if (copy_from_user(&nvme_get_attr, arg, 2 * sizeof(__u32)))
> > + return -EFAULT;
> > +
> > + if (nvme_get_attr.flags != 0)
> > + return -EINVAL;
> > +
> > + switch (nvme_get_attr.argsz) {
> > + case NVME_IOCTL_GET_ATTR_V0SZ:
> > + break;
> > + default:
> > + return -EINVAL;
> > + }
> > + usize = nvme_get_attr.argsz;
> > +
> > + ret = nvme_identify_ctrl(ctrl, &id_ctrl);
> > + if (ret)
> > + return ret;
> > +
> > + ret = nvme_identify_cs_ctrl(ctrl, &id_ctrl_nvm);
> > + if (ret)
> > + return ret;
> > +
> > + nvme_get_attr.argsz = NVME_IOCTL_GET_ATTR_CURSZ;
> > + nvme_get_attr.mpsmin = NVME_CAP_MPSMIN(ctrl->cap);
> > + nvme_get_attr.vsl = id_ctrl_nvm->vsl;
> > + nvme_get_attr.wzsl = id_ctrl_nvm->wzsl;
> > + nvme_get_attr.wusl = id_ctrl_nvm->wusl;
> > + nvme_get_attr.dmrl = id_ctrl_nvm->dmrl;
> > + nvme_get_attr.dmsl = id_ctrl_nvm->dmsl;
> > + nvme_get_attr.dmrsl = id_ctrl_nvm->dmrsl;
> > + nvme_get_attr.oncs = id_ctrl->oncs;
> > + nvme_get_attr.mdts = id_ctrl->mdts;
>
> You already have the 'struct nvme_ctrl' that saves nearly all these
> values. We shouldn't need to send new IO when you can just reference the
> cached values instead.
There are three types of variables here:
1. The variables that are adjusted from what the device actually
returns. Like wzsl that is in max_zeroes_sectors but is already
adjusted with MSPMIN. Here we can de-adjust them if we want to save
an IO call
2. The variables that are not adjusted and are the same in struct
nvme_ctrl in the device. Here we can just use the ctrl member.
3. And the variables that are not in struct nvme_ctrl. Here, we have not
option but to make an IO.
> > + nvme_get_attr.vsl = id_ctrl_nvm->vsl;
Not in ctrl (type 3)
> > + nvme_get_attr.wzsl = id_ctrl_nvm->wzsl;
Exported as ctrl->max_zeroes_sector and adjusted with MPSMIN (type 1)
> > + nvme_get_attr.wusl = id_ctrl_nvm->wusl;
Not in ctrl (type 3)
> > + nvme_get_attr.dmrl = id_ctrl_nvm->dmrl;
In ctrl->max_discard_segments (type 2)
> > + nvme_get_attr.dmsl = id_ctrl_nvm->dmsl;
Not in ctrl (type 3)
> > + nvme_get_attr.dmrsl = id_ctrl_nvm->dmrsl;
In ctrl->dmrsl (type 2)
> > + nvme_get_attr.oncs = id_ctrl->oncs;
In ctrl->oncs (type 2)
> > + nvme_get_attr.mdts = id_ctrl->mdts;
Exported as ctrl->max_hw_sectors and adjusted with MPSMIN (type1)
So I see 3 members in struct id_ctrl_nvm that are not contained in
struct nvme_ctrl, therefore we need an IO to populate these.
To save an IO for the 2 last members (oncs and mdts), then I'll
de-adjust mdts and leave oncs as it is in nvme_ctrl.
>
>
> > +struct nvme_get_attr {
> > + __u32 argsz;
> > + __u32 flags;
> > +
> > + /*
> > + * Memory Page Size MINimum : The host should not configure a page size that
> > + * is larger than (2 ^ (12 + mpsmin)). Comes from [3]
> > + */
> > + __u32 mpsmin;
> > +
> > + /*
> > + * Verify Size Limit : Recommended or supported data size for a verify
> > + * command. From [2].
> > + */
> > + __u8 vsl;
> > +
> > + /*
> > + * Write Zeroes Size Limit : Recommended or supported data size for a
> > + * zeroes command. From [2].
> > + */
> > + __u8 wzsl;
> > +
> > + /*
> > + * Write Uncorrected Size Limit : Recommended or supported data size for
> > + * an uncorrected command. From [2].
> > + */
> > + __u8 wusl;
> > +
> > + /*
> > + * Dataset Management Ranges Limit : Recommended or supported maximum
> > + * number of logical block ranges for the Dataset Management Command.
> > + * From [2].
> > + */
> > + __u8 dmrl;
> > +
> > + /*
> > + * Dataset Management Size Limit : Recommended or supported maximum of
> > + * total number of logical blocks for a Dataset Management Command.
> > + * From [2].
> > + */
> > + __le64 dmsl;
> > +
> > + /*
> > + * Dataset Management Range Size Limit : Recommended or supported maximum
> > + * number of logical blocks in a range of a Dataset Management Command.
> > + * From [2].
> > + */
> > + __le32 dmrsl;
> > +
> > + /*
> > + * Optional NVM Command Support. Is needed to make sense of attributes
> > + * like vsl, wzsl, wusl... Comes from [1].
> > + */
> > + __le16 oncs;
>
> Don't use the little-endian format for values that are not going over
> the wire.
oops. That is mistake. thx
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next prev parent reply other threads:[~2022-10-28 10:38 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20221027160102eucas1p1bb39a9a2b8ed6b54f854849532359332@eucas1p1.samsung.com>
2022-10-27 15:57 ` [RFC 0/3] nvme : Add ioctl to query nvme device attributes Joel Granados
[not found] ` <CGME20221027160108eucas1p223383fc27ba0a27a38f7b768c562a1ed@eucas1p2.samsung.com>
2022-10-27 15:57 ` [RFC 1/3] nvme: Return -ENOMEM when kzalloc fails Joel Granados
2022-10-27 16:26 ` Keith Busch
2022-10-28 9:07 ` Joel Granados
2022-10-30 8:02 ` Christoph Hellwig
2022-10-31 12:36 ` Joel Granados
[not found] ` <CGME20221027160108eucas1p1cc1351fd8bf35ef6e5220e0cdc865ff4@eucas1p1.samsung.com>
2022-10-27 15:57 ` [RFC 2/3] nvme: Move nvme identify CS to separate function Joel Granados
[not found] ` <CGME20221027160108eucas1p2722b30a1be27a855e2b0f2495fed15ab@eucas1p2.samsung.com>
2022-10-27 15:57 ` [RFC 3/3] nvme : Add ioctl to query nvme attributes Joel Granados
2022-10-27 16:55 ` Keith Busch
2022-10-28 10:38 ` Joel Granados [this message]
2022-10-28 14:52 ` Keith Busch
2022-10-28 15:52 ` Joel Granados
2022-10-28 16:22 ` Keith Busch
2022-10-31 12:24 ` Joel Granados
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