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authorJens Axboe <jens.axboe@oracle.com>2008-09-13 20:26:01 +0200
committerJens Axboe <jens.axboe@oracle.com>2008-10-09 08:56:09 +0200
commitc7c22e4d5c1fdebfac4dba76de7d0338c2b0d832 (patch)
treeecc3d2517b3471ccc35d4cb4e3b48d4b57205061 /include/linux/bio.h
parent18887ad910e56066233a07fd3cfb2fa11338b782 (diff)
downloadblackbird-op-linux-c7c22e4d5c1fdebfac4dba76de7d0338c2b0d832.tar.gz
blackbird-op-linux-c7c22e4d5c1fdebfac4dba76de7d0338c2b0d832.zip
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.h11
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 2c0c09034fd2..13aba20edb2d 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
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