From: Kanchan Joshi <[email protected]>
To: Matthew Wilcox <[email protected]>
Cc: Christoph Hellwig <[email protected]>,
Jens Axboe <[email protected]>, Kanchan Joshi <[email protected]>,
[email protected], [email protected], [email protected],
[email protected], [email protected],
"Matias Bj??rling" <[email protected]>,
[email protected], [email protected],
[email protected], [email protected],
Selvakumar S <[email protected]>,
Nitesh Shetty <[email protected]>,
Javier Gonzalez <[email protected]>
Subject: Re: [PATCH v3 4/4] io_uring: add support for zone-append
Date: Mon, 20 Jul 2020 22:19:57 +0530 [thread overview]
Message-ID: <CA+1E3r+j=amkEg-_KUKSiu6gt2TRU6AU-_jwnB1C6wHHKnptfQ@mail.gmail.com> (raw)
In-Reply-To: <CA+1E3rKOZUz7oZ_DGW6xZPQaDu+T5iEKXctd+gsJw05VwpGQSQ@mail.gmail.com>
On Fri, Jul 10, 2020 at 7:41 PM Kanchan Joshi <[email protected]> wrote:
>
> On Fri, Jul 10, 2020 at 7:21 PM Matthew Wilcox <[email protected]> wrote:
> >
> > On Fri, Jul 10, 2020 at 02:49:32PM +0100, Christoph Hellwig wrote:
> > > On Fri, Jul 10, 2020 at 02:48:24PM +0100, Matthew Wilcox wrote:
> > > > If we're going to go the route of changing the CQE, how about:
> > > >
> > > > struct io_uring_cqe {
> > > > __u64 user_data; /* sqe->data submission passed back */
> > > > - __s32 res; /* result code for this event */
> > > > - __u32 flags;
> > > > + union {
> > > > + struct {
> > > > + __s32 res; /* result code for this event */
> > > > + __u32 flags;
> > > > + };
> > > > + __s64 res64;
> > > > + };
> > > > };
> > > >
> > > > then we don't need to change the CQE size and it just depends on the SQE
> > > > whether the CQE for it uses res+flags or res64.
> > >
> > > How do you return a status code or short write when you just have
> > > a u64 that is needed for the offset?
> >
> > it's an s64 not a u64 so you can return a negative errno. i didn't
> > think we allowed short writes for objects-which-have-a-pos.
>
> If we are doing this for zone-append (and not general cases), "__s64
> res64" should work -.
> 64 bits = 1 (sign) + 23 (bytes-copied: cqe->res) + 40
> (written-location: chunk_sector bytes limit)
And this is for the scheme when single CQE is used with bits
refactoring into "_s64 res64" instead of res/flags.
41 bits for zone-append completion = in bytes, sufficient to cover
chunk_sectors size zone
1+22 bits for zone-append bytes-copied = can cover 4MB bytes copied
(single I/O is capped at 4MB in NVMe)
+ * zone-append specific flags
+#define APPEND_OFFSET_BITS (41)
+#define APPEND_RES_BITS (23)
+
+/*
* IO completion data structure (Completion Queue Entry)
*/
struct io_uring_cqe {
- __u64 user_data; /* sqe->data submission passed back */
- __s32 res; /* result code for this event */
- __u32 flags;
+ __u64 user_data; /* sqe->data submission passed back */
+ union {
+ struct {
+ __s32 res; /* result code for
this event */
+ __u32 flags;
+ };
+ /* Alternate for zone-append */
+ struct {
+ union {
+ /*
+ * kernel uses this to store append result
+ * Most significant 23 bits to return number of
+ * bytes or error, and least significant 41 bits
+ * to return zone-relative offset in bytes
+ * */
+ __s64 res64;
+ /*for user-space ease, kernel does not use*/
+ struct {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+ __u64 append_offset :
APPEND_OFFSET_BITS;
+ __s32 append_res : APPEND_RES_BITS;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+ __s32 append_res : APPEND_RES_BITS;
+ __u64 append_offset :
APPEND_OFFSET_BITS;
+#endif
+ }__attribute__ ((__packed__));
+ };
+ };
+ };
};
--
Joshi
next prev parent reply other threads:[~2020-07-20 16:50 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200705185204epcas5p3adeb4fc3473c5fc0472a7396783c5267@epcas5p3.samsung.com>
2020-07-05 18:47 ` [PATCH v3 0/4] zone-append support in io-uring and aio Kanchan Joshi
[not found] ` <CGME20200705185211epcas5p4059d05d2fcedb91829300a7a7d03fda3@epcas5p4.samsung.com>
2020-07-05 18:47 ` [PATCH v3 1/4] fs: introduce FMODE_ZONE_APPEND and IOCB_ZONE_APPEND Kanchan Joshi
[not found] ` <CGME20200705185217epcas5p1cc12d4b892f057a1fe06d73a00869daa@epcas5p1.samsung.com>
2020-07-05 18:47 ` [PATCH v3 2/4] block: add zone append handling for direct I/O path Kanchan Joshi
[not found] ` <CGME20200705185221epcas5p28b6d060df829b751109265222285da0e@epcas5p2.samsung.com>
2020-07-05 18:47 ` [PATCH v3 3/4] block: enable zone-append for iov_iter of bvec type Kanchan Joshi
[not found] ` <CGME20200705185227epcas5p16fba3cb92561794b960184c89fdf2bb7@epcas5p1.samsung.com>
2020-07-05 18:47 ` [PATCH v3 4/4] io_uring: add support for zone-append Kanchan Joshi
2020-07-05 21:00 ` Jens Axboe
2020-07-05 21:09 ` Matthew Wilcox
2020-07-05 21:12 ` Jens Axboe
2020-07-06 14:10 ` Matthew Wilcox
2020-07-06 14:27 ` Jens Axboe
2020-07-06 14:32 ` Matthew Wilcox
2020-07-06 14:33 ` Jens Axboe
2020-07-07 15:11 ` Kanchan Joshi
2020-07-07 15:52 ` Matthew Wilcox
2020-07-07 16:00 ` Christoph Hellwig
2020-07-07 20:23 ` Kanchan Joshi
2020-07-07 20:40 ` Jens Axboe
2020-07-07 22:18 ` Matthew Wilcox
2020-07-07 22:37 ` Jens Axboe
2020-07-08 12:58 ` Kanchan Joshi
2020-07-08 14:22 ` Matthew Wilcox
2020-07-08 16:41 ` Kanchan Joshi
2020-07-08 14:54 ` Jens Axboe
2020-07-08 14:58 ` Matthew Wilcox
2020-07-08 14:59 ` Jens Axboe
2020-07-08 15:02 ` Matthew Wilcox
2020-07-08 15:06 ` Jens Axboe
2020-07-08 16:08 ` Javier González
2020-07-08 16:33 ` Matthew Wilcox
2020-07-08 16:38 ` Jens Axboe
2020-07-08 17:13 ` Kanchan Joshi
2020-07-08 16:43 ` Javier González
2020-07-06 13:58 ` Kanchan Joshi
2020-07-09 10:15 ` Christoph Hellwig
2020-07-09 13:58 ` Jens Axboe
2020-07-09 14:00 ` Christoph Hellwig
2020-07-09 14:05 ` Jens Axboe
2020-07-09 18:36 ` Kanchan Joshi
2020-07-09 18:50 ` Pavel Begunkov
2020-07-09 18:53 ` Pavel Begunkov
2020-07-09 18:50 ` Jens Axboe
2020-07-09 19:05 ` Kanchan Joshi
2020-07-10 13:10 ` Christoph Hellwig
2020-07-10 13:48 ` Matthew Wilcox
2020-07-10 13:49 ` Christoph Hellwig
2020-07-10 13:51 ` Matthew Wilcox
2020-07-10 14:11 ` Kanchan Joshi
2020-07-20 16:49 ` Kanchan Joshi [this message]
2020-07-20 17:14 ` Matthew Wilcox
2020-07-20 20:17 ` Kanchan Joshi
2020-07-21 0:59 ` Damien Le Moal
2020-07-21 1:15 ` Matthew Wilcox
2020-07-21 1:29 ` Jens Axboe
2020-07-21 2:19 ` Damien Le Moal
2020-07-10 14:09 ` Jens Axboe
2020-07-20 16:46 ` Kanchan Joshi
2020-07-10 13:09 ` Christoph Hellwig
2020-07-10 13:29 ` Kanchan Joshi
2020-07-10 13:43 ` Christoph Hellwig
2020-07-20 17:02 ` Kanchan Joshi
2020-07-10 13:57 ` Kanchan Joshi
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