diff options
| author | Jens Axboe <jens.axboe@oracle.com> | 2008-09-13 20:26:01 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2008-10-09 08:56:09 +0200 |
| commit | c7c22e4d5c1fdebfac4dba76de7d0338c2b0d832 (patch) | |
| tree | ecc3d2517b3471ccc35d4cb4e3b48d4b57205061 /include/linux/bio.h | |
| parent | 18887ad910e56066233a07fd3cfb2fa11338b782 (diff) | |
block: add support for IO CPU affinity
This patch adds support for controlling the IO completion CPU of
either all requests on a queue, or on a per-request basis. We export
a sysfs variable (rq_affinity) which, if set, migrates completions
of requests to the CPU that originally submitted it. A bio helper
(bio_set_completion_cpu()) is also added, so that queuers can ask
for completion on that specific CPU.
In testing, this has been show to cut the system time by as much
as 20-40% on synthetic workloads where CPU affinity is desired.
This requires a little help from the architecture, so it'll only
work as designed for archs that are using the new generic smp
helper infrastructure.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'include/linux/bio.h')
| -rw-r--r-- | include/linux/bio.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/bio.h b/include/linux/bio.h index 2c0c09034fd..13aba20edb2 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -81,6 +81,8 @@ struct bio { unsigned int bi_max_vecs; /* max bvl_vecs we can hold */ + unsigned int bi_comp_cpu; /* completion CPU */ + struct bio_vec *bi_io_vec; /* the actual vec list */ bio_end_io_t *bi_end_io; @@ -105,6 +107,7 @@ struct bio { #define BIO_BOUNCED 5 /* bio is a bounce bio */ #define BIO_USER_MAPPED 6 /* contains user pages */ #define BIO_EOPNOTSUPP 7 /* not supported */ +#define BIO_CPU_AFFINE 8 /* complete bio on same CPU as submitted */ #define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag))) /* @@ -343,6 +346,14 @@ extern struct bio_vec *bvec_alloc_bs(gfp_t, int, unsigned long *, struct bio_set extern unsigned int bvec_nr_vecs(unsigned short idx); /* + * Allow queuer to specify a completion CPU for this bio + */ +static inline void bio_set_completion_cpu(struct bio *bio, unsigned int cpu) +{ + bio->bi_comp_cpu = cpu; +} + +/* * bio_set is used to allow other portions of the IO system to * allocate their own private memory pools for bio and iovec structures. * These memory pools in turn all allocate from the bio_slab |