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| author | ps <ps@FreeBSD.org> | 2004-12-10 03:27:12 +0000 |
|---|---|---|
| committer | ps <ps@FreeBSD.org> | 2004-12-10 03:27:12 +0000 |
| commit | f46c52047f3fcd319847f2c25bb66800bb5d6b2d (patch) | |
| tree | f9c631fca29de61464b46ce9d29d3fe6c3db1b04 /sys/nfsclient/nfs_bio.c | |
| parent | f1047725903546a5213ec64e66e804876ad8f471 (diff) | |
| download | FreeBSD-src-f46c52047f3fcd319847f2c25bb66800bb5d6b2d.zip FreeBSD-src-f46c52047f3fcd319847f2c25bb66800bb5d6b2d.tar.gz | |
Store a hint in the nfsnode to detect sequential access of the file.
Kick off a readahead only when sequential access is detected. This
eliminates wasteful readaheads in random file access.
Submitted by: Mohan Srinivasan mohans at yahoo-inc dot com
Obtained from: Yahoo!
Diffstat (limited to 'sys/nfsclient/nfs_bio.c')
| -rw-r--r-- | sys/nfsclient/nfs_bio.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/sys/nfsclient/nfs_bio.c b/sys/nfsclient/nfs_bio.c index 9e9af49..c6eea93 100644 --- a/sys/nfsclient/nfs_bio.c +++ b/sys/nfsclient/nfs_bio.c @@ -421,8 +421,10 @@ nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred) /* * Start the read ahead(s), as required. + * The readahead is kicked off only if sequential access + * is detected, based on the readahead hint (ra_expect_lbn). */ - if (nmp->nm_readahead > 0) { + if (nmp->nm_readahead > 0 && np->ra_expect_lbn == lbn) { for (nra = 0; nra < nmp->nm_readahead && nra < seqcount && (off_t)(lbn + 1 + nra) * biosize < np->n_size; nra++) { rabn = lbn + 1 + nra; @@ -448,6 +450,7 @@ nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred) } } } + np->ra_expect_lbn = lbn + 1; } /* |
