Hi, Trond.
I wrote "is_partially_uptodate" aops for nfs client named nfs_is_partially_uptodate().
This aops checks that nfs_page is attached to a page and read IO to a page is
within the range between wb_pgbase and wb_pgbase + wb_bytes of the nfs_page.
If this aops succeed, we do not have to issue actual read IO to NFS server
even if a page is not uptodate because the portion we want to read are uptodate.
So with this patch random read/write mixed workloads or random read after random write
workloads can be optimized and we can get performance improvement.
I did benchmark test using sysbench.
sysbench --num-threads=16 --max-requests=100000 --test=fileio --file-block-size=2K
--file-total-size=200M --file-test-mode=rndrw --file-fsync-freq=0
--file-rw-ratio=0.5 run
The result was:
-2.6.29-rc4
Operations performed: 33356 Read, 66682 Write, 128 Other = 100166 Total
Read 65.148Mb Written 130.24Mb Total transferred 195.39Mb (3.1093Mb/sec)
1591.97 Requests/sec executed
Test execution summary:
total time: 62.8391s
total number of events: 100038
total time taken by event execution: 841.7603
per-request statistics:
min: 0.0000s
avg: 0.0084s
max: 16.4564s
approx. 95 percentile: 0.0446s
Threads fairness:
events (avg/stddev): 6252.3750/306.48
execution time (avg/stddev): 52.6100/0.38
-2.6.29-rc4 + patch
Operations performed: 33346 Read, 66662 Write, 128 Other = 100136 Total
Read 65.129Mb Written 130.2Mb Total transferred 195.33Mb (5.0113Mb/sec)
2565.81 Requests/sec executed
Test execution summary:
total time: 38.9772s
total number of events: 100008
total time taken by event execution: 339.6821
per-request statistics:
min: 0.0000s
avg: 0.0034s
max: 1.6768s
approx. 95 percentile: 0.0200s
Threads fairness:
events (avg/stddev): 6250.5000/302.04
execution time (avg/stddev): 21.2301/0.45
I/O performance was significantly improved by following patch.
Please merge my patch.
Thanks.
Signed-off-by: Hisashi Hifumi <hifumi.hisashi@xxxxxxxxxxxxx>
diff -Nrup linux-2.6.29-rc5.org/fs/nfs/file.c linux-2.6.29-rc5/fs/nfs/file.c
--- linux-2.6.29-rc5.org/fs/nfs/file.c 2009-02-16 12:31:18.000000000 +0900
+++ linux-2.6.29-rc5/fs/nfs/file.c 2009-02-16 13:05:29.000000000 +0900
@@ -449,6 +449,7 @@ const struct address_space_operations nf
.releasepage = nfs_release_page,
.direct_IO = nfs_direct_IO,
.launder_page = nfs_launder_page,
+ .is_partially_uptodate = nfs_is_partially_uptodate,
};
static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct page *page)
diff -Nrup linux-2.6.29-rc5.org/fs/nfs/read.c linux-2.6.29-rc5/fs/nfs/read.c
--- linux-2.6.29-rc5.org/fs/nfs/read.c 2009-02-16 12:31:18.000000000 +0900
+++ linux-2.6.29-rc5/fs/nfs/read.c 2009-02-16 13:05:29.000000000 +0900
@@ -599,6 +599,33 @@ out:
return ret;
}
+int nfs_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
+ unsigned long from)
+{
+ struct inode *inode = page->mapping->host;
+ unsigned to;
+ struct nfs_page *req = NULL;
+
+ spin_lock(&inode->i_lock);
+ if (PagePrivate(page)) {
+ req = (struct nfs_page *)page_private(page);
+ if (req)
+ kref_get(&req->wb_kref);
+ }
+ spin_unlock(&inode->i_lock);
+ if (!req)
+ return 0;
+
+ to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count);
+ to = from + to;
+ if (from >= req->wb_pgbase && to <= req->wb_pgbase + req->wb_bytes) {
+ nfs_release_request(req);
+ return 1;
+ }
+ nfs_release_request(req);
+ return 0;
+}
+
int __init nfs_init_readpagecache(void)
{
nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
diff -Nrup linux-2.6.29-rc5.org/include/linux/nfs_fs.h linux-2.6.29-rc5/include/linux/nfs_fs.h
--- linux-2.6.29-rc5.org/include/linux/nfs_fs.h 2009-02-16 12:31:18.000000000 +0900
+++ linux-2.6.29-rc5/include/linux/nfs_fs.h 2009-02-16 13:05:29.000000000 +0900
@@ -506,6 +506,9 @@ extern int nfs_readpages(struct file *,
struct list_head *, unsigned);
extern int nfs_readpage_result(struct rpc_task *, struct nfs_read_data *);
extern void nfs_readdata_release(void *data);
+extern int nfs_is_partially_uptodate(struct page *, read_descriptor_t *,
+ unsigned long);
+
/*
* Allocate nfs_read_data structures
--
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