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Subject[patch v2 3/8]block: fiops sync/async scale
CFQ gives 2.5 times more share to sync workload. This matches CFQ.

Note this is different with the read/write scale. We have 3 types of
requests:
1. read
2. sync write
3. write
CFQ doesn't differentitate type 1 and 2, but request cost of 1 and 2
are usually different for flash based storage. So we have both sync/async
and read/write scale here.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
---
block/fiops-iosched.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
Index: linux/block/fiops-iosched.c
===================================================================
--- linux.orig/block/fiops-iosched.c 2012-01-18 14:33:51.000000000 +0800
+++ linux/block/fiops-iosched.c 2012-01-18 14:33:59.000000000 +0800
@@ -17,6 +17,8 @@

#define VIOS_READ_SCALE (1)
#define VIOS_WRITE_SCALE (1)
+#define VIOS_SYNC_SCALE (2)
+#define VIOS_ASYNC_SCALE (5)

struct fiops_rb_root {
struct rb_root rb;
@@ -39,6 +41,8 @@ struct fiops_data {

unsigned int read_scale;
unsigned int write_scale;
+ unsigned int sync_scale;
+ unsigned int async_scale;
};

struct fiops_ioc {
@@ -291,6 +295,9 @@ static u64 fiops_scaled_vios(struct fiop
if (rq_data_dir(rq) == WRITE)
vios = vios * fiopsd->write_scale / fiopsd->read_scale;

+ if (!rq_is_sync(rq))
+ vios = vios * fiopsd->async_scale / fiopsd->sync_scale;
+
return vios;
}

@@ -513,6 +520,8 @@ static void *fiops_init_queue(struct req

fiopsd->read_scale = VIOS_READ_SCALE;
fiopsd->write_scale = VIOS_WRITE_SCALE;
+ fiopsd->sync_scale = VIOS_SYNC_SCALE;
+ fiopsd->async_scale = VIOS_ASYNC_SCALE;

return fiopsd;
}
@@ -557,6 +566,8 @@ static ssize_t __FUNC(struct elevator_qu
}
SHOW_FUNCTION(fiops_read_scale_show, fiopsd->read_scale);
SHOW_FUNCTION(fiops_write_scale_show, fiopsd->write_scale);
+SHOW_FUNCTION(fiops_sync_scale_show, fiopsd->sync_scale);
+SHOW_FUNCTION(fiops_async_scale_show, fiopsd->async_scale);
#undef SHOW_FUNCTION

#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \
@@ -574,6 +585,8 @@ static ssize_t __FUNC(struct elevator_qu
}
STORE_FUNCTION(fiops_read_scale_store, &fiopsd->read_scale, 1, 100);
STORE_FUNCTION(fiops_write_scale_store, &fiopsd->write_scale, 1, 100);
+STORE_FUNCTION(fiops_sync_scale_store, &fiopsd->sync_scale, 1, 100);
+STORE_FUNCTION(fiops_async_scale_store, &fiopsd->async_scale, 1, 100);
#undef STORE_FUNCTION

#define FIOPS_ATTR(name) \
@@ -582,6 +595,8 @@ STORE_FUNCTION(fiops_write_scale_store,
static struct elv_fs_entry fiops_attrs[] = {
FIOPS_ATTR(read_scale),
FIOPS_ATTR(write_scale),
+ FIOPS_ATTR(sync_scale),
+ FIOPS_ATTR(async_scale),
__ATTR_NULL
};



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