Add a readahead heuristic to the NFS server side code. While the server
cannot unilaterally pass data to a client it can reduce the physical
disk transaction overhead by reading larger blocks. This results in
better pipelining of requests/responses over the network and an almost
100% increase in cpu efficiency on the server. On a 100BaseTX network
NFS read performance increases from 8.5 MBytes/sec to 10 MB/sec (maxed
out), and cpu efficiency increases from 72% idle to 80% idle on the server.
Reviewed by: Alfred Perlstein <bright@wintelcom.net>
This commit is contained in:
dillon
parent
0a7cf7b859
commit
bab004e729
@ -115,6 +115,18 @@
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#define MAX_COMMIT_COUNT (1024 * 1024)
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#define NUM_HEURISTIC 64
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#define NHUSE_INIT 64
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#define NHUSE_INC 16
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#define NHUSE_MAX 2048
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static struct nfsheur {
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struct vnode *nh_vp; /* vp to match (unreferenced pointer) */
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off_t nh_nextr; /* next offset for sequential detection */
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int nh_use; /* use count for selection */
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int nh_seqcount; /* heuristic */
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} nfsheur[NUM_HEURISTIC];
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nfstype nfsv3_type[9] = { NFNON, NFREG, NFDIR, NFBLK, NFCHR, NFLNK, NFSOCK,
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NFFIFO, NFNON };
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#ifndef NFS_NOSERVER
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@ -780,7 +792,9 @@ nfsrv_read(nfsd, slp, procp, mrq)
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fhandle_t *fhp;
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struct uio io, *uiop = &io;
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struct vattr va, *vap = &va;
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struct nfsheur *nh;
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off_t off;
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int ioflag = 0;
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u_quad_t frev;
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nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
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@ -833,12 +847,73 @@ nfsrv_read(nfsd, slp, procp, mrq)
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error = 0;
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goto nfsmout;
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}
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/*
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* Calculate byte count to read
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*/
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if (off >= vap->va_size)
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cnt = 0;
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else if ((off + reqlen) > vap->va_size)
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cnt = vap->va_size - off;
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else
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cnt = reqlen;
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/*
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* Calculate seqcount for heuristic
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*/
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{
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int hi;
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int try = 4;
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/*
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* Locate best candidate
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*/
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hi = ((int)vp / sizeof(struct vnode)) & (NUM_HEURISTIC - 1);
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nh = &nfsheur[hi];
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while (try--) {
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if (nfsheur[hi].nh_vp == vp) {
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nh = &nfsheur[hi];
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break;
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}
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if (nfsheur[hi].nh_use > 0)
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--nfsheur[hi].nh_use;
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hi = (hi + 1) & (NUM_HEURISTIC - 1);
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if (nfsheur[hi].nh_use < nh->nh_use)
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nh = &nfsheur[hi];
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}
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if (nh->nh_vp != vp) {
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nh->nh_vp = vp;
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nh->nh_nextr = off;
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nh->nh_use = NHUSE_INIT;
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if (off == 0)
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nh->nh_seqcount = 4;
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else
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nh->nh_seqcount = 1;
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}
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/*
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* Calculate heuristic
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*/
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if ((off == 0 && nh->nh_seqcount > 0) || off == nh->nh_nextr) {
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if (++nh->nh_seqcount > 127)
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nh->nh_seqcount = 127;
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} else if (nh->nh_seqcount > 1) {
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nh->nh_seqcount = 1;
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} else {
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nh->nh_seqcount = 0;
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}
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nh->nh_use += NHUSE_INC;
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if (nh->nh_use > NHUSE_MAX)
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nh->nh_use = NHUSE_MAX;
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ioflag |= nh->nh_seqcount << 16;
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}
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nfsm_reply(NFSX_POSTOPORFATTR(v3) + 3 * NFSX_UNSIGNED+nfsm_rndup(cnt));
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if (v3) {
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nfsm_build(tl, u_int32_t *, NFSX_V3FATTR + 4 * NFSX_UNSIGNED);
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@ -896,8 +971,9 @@ nfsrv_read(nfsd, slp, procp, mrq)
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uiop->uio_resid = len;
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uiop->uio_rw = UIO_READ;
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uiop->uio_segflg = UIO_SYSSPACE;
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error = VOP_READ(vp, uiop, IO_NODELOCKED, cred);
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error = VOP_READ(vp, uiop, IO_NODELOCKED | ioflag, cred);
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off = uiop->uio_offset;
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nh->nh_nextr = off;
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FREE((caddr_t)iv2, M_TEMP);
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if (error || (getret = VOP_GETATTR(vp, vap, cred, procp))) {
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if (!error)
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@ -115,6 +115,18 @@
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#define MAX_COMMIT_COUNT (1024 * 1024)
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#define NUM_HEURISTIC 64
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#define NHUSE_INIT 64
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#define NHUSE_INC 16
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#define NHUSE_MAX 2048
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static struct nfsheur {
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struct vnode *nh_vp; /* vp to match (unreferenced pointer) */
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off_t nh_nextr; /* next offset for sequential detection */
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int nh_use; /* use count for selection */
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int nh_seqcount; /* heuristic */
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} nfsheur[NUM_HEURISTIC];
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nfstype nfsv3_type[9] = { NFNON, NFREG, NFDIR, NFBLK, NFCHR, NFLNK, NFSOCK,
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NFFIFO, NFNON };
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#ifndef NFS_NOSERVER
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@ -780,7 +792,9 @@ nfsrv_read(nfsd, slp, procp, mrq)
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fhandle_t *fhp;
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struct uio io, *uiop = &io;
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struct vattr va, *vap = &va;
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struct nfsheur *nh;
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off_t off;
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int ioflag = 0;
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u_quad_t frev;
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nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
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@ -833,12 +847,73 @@ nfsrv_read(nfsd, slp, procp, mrq)
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error = 0;
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goto nfsmout;
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}
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/*
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* Calculate byte count to read
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*/
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if (off >= vap->va_size)
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cnt = 0;
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else if ((off + reqlen) > vap->va_size)
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cnt = vap->va_size - off;
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else
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cnt = reqlen;
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/*
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* Calculate seqcount for heuristic
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*/
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{
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int hi;
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int try = 4;
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/*
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* Locate best candidate
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*/
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hi = ((int)vp / sizeof(struct vnode)) & (NUM_HEURISTIC - 1);
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nh = &nfsheur[hi];
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while (try--) {
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if (nfsheur[hi].nh_vp == vp) {
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nh = &nfsheur[hi];
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break;
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}
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if (nfsheur[hi].nh_use > 0)
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--nfsheur[hi].nh_use;
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hi = (hi + 1) & (NUM_HEURISTIC - 1);
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if (nfsheur[hi].nh_use < nh->nh_use)
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nh = &nfsheur[hi];
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}
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if (nh->nh_vp != vp) {
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nh->nh_vp = vp;
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nh->nh_nextr = off;
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nh->nh_use = NHUSE_INIT;
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if (off == 0)
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nh->nh_seqcount = 4;
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else
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nh->nh_seqcount = 1;
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}
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/*
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* Calculate heuristic
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*/
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if ((off == 0 && nh->nh_seqcount > 0) || off == nh->nh_nextr) {
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if (++nh->nh_seqcount > 127)
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nh->nh_seqcount = 127;
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} else if (nh->nh_seqcount > 1) {
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nh->nh_seqcount = 1;
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} else {
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nh->nh_seqcount = 0;
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}
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nh->nh_use += NHUSE_INC;
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if (nh->nh_use > NHUSE_MAX)
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nh->nh_use = NHUSE_MAX;
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ioflag |= nh->nh_seqcount << 16;
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}
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nfsm_reply(NFSX_POSTOPORFATTR(v3) + 3 * NFSX_UNSIGNED+nfsm_rndup(cnt));
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if (v3) {
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nfsm_build(tl, u_int32_t *, NFSX_V3FATTR + 4 * NFSX_UNSIGNED);
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@ -896,8 +971,9 @@ nfsrv_read(nfsd, slp, procp, mrq)
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uiop->uio_resid = len;
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uiop->uio_rw = UIO_READ;
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uiop->uio_segflg = UIO_SYSSPACE;
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error = VOP_READ(vp, uiop, IO_NODELOCKED, cred);
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error = VOP_READ(vp, uiop, IO_NODELOCKED | ioflag, cred);
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off = uiop->uio_offset;
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nh->nh_nextr = off;
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FREE((caddr_t)iv2, M_TEMP);
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if (error || (getret = VOP_GETATTR(vp, vap, cred, procp))) {
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if (!error)
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