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Add BIO_SPEEDUP

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Add BIO_SPEEDUP bio command and g_io_speedup wrapper. It tells the
lower layers that the upper layers are dealing with some shortage
(dirty pages and/or disk blocks). The lower layers should do what they
can to speed up anything that's been delayed.

The first use will be to tell the CAM I/O scheduler that any TRIM
shaping should be short-circuited because the system needs
blocks. We'll also call it when there's too many resources used by
UFS.

Reviewed by: kirk, kib
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D18351
This commit is contained in:
Warner Losh 2019-12-17 00:13:35 +00:00
parent 7918ea40a5
commit b182c79211
3 changed files with 41 additions and 0 deletions
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1
sys/geom/geom.h
View File

@ -343,6 +343,7 @@ void g_io_deliver(struct bio *bp, int error);
int g_io_getattr(const char *attr, struct g_consumer *cp, int *len, void *ptr);
int g_io_zonecmd(struct disk_zone_args *zone_args, struct g_consumer *cp);
int g_io_flush(struct g_consumer *cp);
int g_io_speedup(size_t shortage, u_int flags, size_t *resid, struct g_consumer *cp);
int g_register_classifier(struct g_classifier_hook *hook);
void g_unregister_classifier(struct g_classifier_hook *hook);
void g_io_request(struct bio *bp, struct g_consumer *cp);

36
sys/geom/geom_io.c
View File

@ -340,6 +340,42 @@ g_io_zonecmd(struct disk_zone_args *zone_args, struct g_consumer *cp)
return (error);
}
/*
* Send a BIO_SPEEDUP down the stack. This is used to tell the lower layers that
* the upper layers have detected a resource shortage. The lower layers are
* advised to stop delaying I/O that they might be holding for performance
* reasons and to schedule it (non-trims) or complete it successfully (trims) as
* quickly as it can. bio_length is the amount of the shortage. This call
* should be non-blocking. bio_resid is used to communicate back if the lower
* layers couldn't find bio_length worth of I/O to schedule or discard. A length
* of 0 means to do as much as you can (schedule the h/w queues full, discard
* all trims). flags are a hint from the upper layers to the lower layers what
* operation should be done.
*/
int
g_io_speedup(size_t shortage, u_int flags, size_t *resid, struct g_consumer *cp)
{
struct bio *bp;
int error;
KASSERT((flags & (BIO_SPEEDUP_TRIM | BIO_SPEEDUP_WRITE)) != 0,
("Invalid flags passed to g_io_speedup: %#x", flags));
g_trace(G_T_BIO, "bio_speedup(%s, %zu, %#x)", cp->provider->name,
shortage, flags);
bp = g_new_bio();
if (bp == NULL)
return (ENOMEM);
bp->bio_cmd = BIO_SPEEDUP;
bp->bio_length = shortage;
bp->bio_done = NULL;
bp->bio_flags |= flags;
g_io_request(bp, cp);
error = biowait(bp, "gflush");
*resid = bp->bio_resid;
g_destroy_bio(bp);
return (error);
}
int
g_io_flush(struct g_consumer *cp)
{

4
sys/sys/bio.h
View File

@ -53,6 +53,7 @@
#define BIO_CMD1 0x07 /* Available for local hacks */
#define BIO_CMD2 0x08 /* Available for local hacks */
#define BIO_ZONE 0x09 /* Zone command */
#define BIO_SPEEDUP 0x0a /* Upper layers face shortage */
/* bio_flags */
#define BIO_ERROR 0x01 /* An error occurred processing this bio. */
@ -70,6 +71,9 @@
#define PRINT_BIO_FLAGS "\20\7vlist\6transient_mapping\5unmapped" \
"\4ordered\3onqueue\2done\1error"
#define BIO_SPEEDUP_WRITE 0x4000 /* Resource shortage at upper layers */
#define BIO_SPEEDUP_TRIM 0x8000 /* Resource shortage at upper layers */
#ifdef _KERNEL
struct disk;
struct bio;