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bdev: add bdev_io optimizations

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First, improve packing of spdk_bdev_io.  Move any
fields which must be zeroed into the first cacheline.
Also change type and status from enums (needing 4 bytes)
to int16_t which is still a far bigger range than
needed.

Next, modify spdk_bdev_get_io to only zero the
first cacheline (actually a bit less).

SPDK_BDEV_IO_TYPE_INVALID is also added, making it
explicit that 0 is an invalid value for the IO type.
Previously this was somewhat inferred.

There are still additional improvements that can
be made to this area - primarily combining
spdk_bdev_get_io() and spdk_bdev_io_init() into
a single function.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: I1916d6d5db02c93622b9725ec1095148e3f384d8

Reviewed-on: https://review.gerrithub.io/377799
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
This commit is contained in:
Jim Harris 2017-09-08 09:27:56 -07:00
parent 0491b3cbc6
commit 70a0bc3096
3 changed files with 15 additions and 14 deletions
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3
include/spdk/bdev.h
View File

@ -81,7 +81,8 @@ struct spdk_bdev_desc;
/** bdev I/O type */
enum spdk_bdev_io_type {
SPDK_BDEV_IO_TYPE_READ = 1,
SPDK_BDEV_IO_TYPE_INVALID = 0,
SPDK_BDEV_IO_TYPE_READ,
SPDK_BDEV_IO_TYPE_WRITE,
SPDK_BDEV_IO_TYPE_UNMAP,
SPDK_BDEV_IO_TYPE_FLUSH,

24
include/spdk_internal/bdev.h
View File

@ -260,7 +260,18 @@ struct spdk_bdev_io {
TAILQ_ENTRY(spdk_bdev_io) buf_link;
/** Enumerated value representing the I/O type. */
enum spdk_bdev_io_type type;
int16_t type;
/** Status for the IO */
int16_t status;
/**
* Set to true while the bdev module submit_request function is in progress.
*
* This is used to decide whether spdk_bdev_io_complete() can complete the I/O directly
* or if completion must be deferred via an event.
*/
bool in_submit_request;
union {
struct {
@ -321,9 +332,6 @@ struct spdk_bdev_io {
} nvme_passthru;
} u;
/** Status for the IO */
enum spdk_bdev_io_status status;
/** Error information from a device */
union {
/** Only valid when status is SPDK_BDEV_IO_STATUS_NVME_ERROR */
@ -352,14 +360,6 @@ struct spdk_bdev_io {
/** Context that will be passed to the completion callback */
void *caller_ctx;
/**
* Set to true while the bdev module submit_request function is in progress.
*
* This is used to decide whether spdk_bdev_io_complete() can complete the I/O directly
* or if completion must be deferred via an event.
*/
bool in_submit_request;
/** Member used for linking child I/Os together. */
TAILQ_ENTRY(spdk_bdev_io) link;

2
lib/bdev/bdev.c
View File

@ -581,7 +581,7 @@ spdk_bdev_get_io(void)
abort();
}
memset(bdev_io, 0, sizeof(*bdev_io));
memset(bdev_io, 0, offsetof(struct spdk_bdev_io, u));
return bdev_io;
}