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| author | Ming Lei <ming.lei@redhat.com> | 2019-04-28 10:39:30 +0300 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2019-06-20 22:21:33 +0300 |
| commit | 4635873c561ac57b66adfcc2487c38106b1c916c (patch) | |
| tree | 328c277fd811943ccf9e8b619e13397009c7f3e6 /include/linux/scatterlist.h | |
| parent | ee5a1dbfec57cc1ffdedf2bd767c84d5e0498ed8 (diff) | |
| download | linux-4635873c561ac57b66adfcc2487c38106b1c916c.tar.xz | |
scsi: lib/sg_pool.c: improve APIs for allocating sg pool
sg_alloc_table_chained() currently allows the caller to provide one
preallocated SGL and returns if the requested number isn't bigger than
size of that SGL. This is used to inline an SGL for an IO request.
However, scattergather code only allows that size of the 1st preallocated
SGL to be SG_CHUNK_SIZE(128). This means a substantial amount of memory
(4KB) is claimed for the SGL for each IO request. If the I/O is small, it
would be prudent to allocate a smaller SGL.
Introduce an extra parameter to sg_alloc_table_chained() and
sg_free_table_chained() for specifying size of the preallocated SGL.
Both __sg_free_table() and __sg_alloc_table() assume that each SGL has the
same size except for the last one. Change the code to allow both functions
to accept a variable size for the 1st preallocated SGL.
[mkp: attempted to clarify commit desc]
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: netdev@vger.kernel.org
Cc: linux-nvme@lists.infradead.org
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'include/linux/scatterlist.h')
| -rw-r--r-- | include/linux/scatterlist.h | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 30a9a55c28ba..6eec50fb36c8 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -266,10 +266,11 @@ int sg_split(struct scatterlist *in, const int in_mapped_nents, typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t); typedef void (sg_free_fn)(struct scatterlist *, unsigned int); -void __sg_free_table(struct sg_table *, unsigned int, bool, sg_free_fn *); +void __sg_free_table(struct sg_table *, unsigned int, unsigned int, + sg_free_fn *); void sg_free_table(struct sg_table *); int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, - struct scatterlist *, gfp_t, sg_alloc_fn *); + struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *); int sg_alloc_table(struct sg_table *, unsigned int, gfp_t); int __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, unsigned int n_pages, unsigned int offset, @@ -331,9 +332,11 @@ size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, #endif #ifdef CONFIG_SG_POOL -void sg_free_table_chained(struct sg_table *table, bool first_chunk); +void sg_free_table_chained(struct sg_table *table, + unsigned nents_first_chunk); int sg_alloc_table_chained(struct sg_table *table, int nents, - struct scatterlist *first_chunk); + struct scatterlist *first_chunk, + unsigned nents_first_chunk); #endif /* |