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Avoid the overhead of acquiring a lock in nfsrv_checkgetattr() when

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there are no write delegations issued.

manu@ reported on the freebsd-current@ mailing list that there was
a significant performance hit in nfsrv_checkgetattr() caused by
the acquisition/release of a state lock, even when there were no
write delegations issued.
This patch add a count of outstanding issued write delegations to the
NFSv4 server. This count allows nfsrv_checkgetattr() to return without
acquiring any lock when the count is 0, avoiding the performance hit
for the case where no write delegations are issued.

Reported by:	manu
Reviewed by:	kib
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D13327
This commit is contained in:
Rick Macklem 2017-12-04 21:50:27 +00:00
parent eb1eebb9aa
commit b07bc39a23
1 changed files with 9 additions and 0 deletions
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9
sys/fs/nfsserver/nfs_nfsdstate.c
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@ -95,6 +95,7 @@ static time_t nfsrvboottime;
static int nfsrv_returnoldstateid = 0, nfsrv_clients = 0;
static int nfsrv_clienthighwater = NFSRV_CLIENTHIGHWATER;
static int nfsrv_nogsscallback = 0;
static volatile int nfsrv_writedelegcnt = 0;
/* local functions */
static void nfsrv_dumpaclient(struct nfsclient *clp,
@ -1263,6 +1264,8 @@ nfsrv_freedeleg(struct nfsstate *stp)
LIST_REMOVE(stp, ls_hash);
LIST_REMOVE(stp, ls_list);
LIST_REMOVE(stp, ls_file);
if ((stp->ls_flags & NFSLCK_DELEGWRITE) != 0)
nfsrv_writedelegcnt--;
lfp = stp->ls_lfp;
if (LIST_EMPTY(&lfp->lf_open) &&
LIST_EMPTY(&lfp->lf_lock) && LIST_EMPTY(&lfp->lf_deleg) &&
@ -2907,6 +2910,7 @@ nfsrv_openctrl(struct nfsrv_descript *nd, vnode_t vp,
new_deleg->ls_flags = (NFSLCK_DELEGWRITE |
NFSLCK_READACCESS | NFSLCK_WRITEACCESS);
*rflagsp |= NFSV4OPEN_WRITEDELEGATE;
nfsrv_writedelegcnt++;
} else {
new_deleg->ls_flags = (NFSLCK_DELEGREAD |
NFSLCK_READACCESS);
@ -3037,6 +3041,7 @@ nfsrv_openctrl(struct nfsrv_descript *nd, vnode_t vp,
new_deleg->ls_clp = clp;
new_deleg->ls_filerev = filerev;
new_deleg->ls_compref = nd->nd_compref;
nfsrv_writedelegcnt++;
LIST_INSERT_HEAD(&lfp->lf_deleg, new_deleg, ls_file);
LIST_INSERT_HEAD(NFSSTATEHASH(clp,
new_deleg->ls_stateid), new_deleg, ls_hash);
@ -3094,6 +3099,7 @@ nfsrv_openctrl(struct nfsrv_descript *nd, vnode_t vp,
new_deleg->ls_flags = (NFSLCK_DELEGWRITE |
NFSLCK_READACCESS | NFSLCK_WRITEACCESS);
*rflagsp |= NFSV4OPEN_WRITEDELEGATE;
nfsrv_writedelegcnt++;
} else {
new_deleg->ls_flags = (NFSLCK_DELEGREAD |
NFSLCK_READACCESS);
@ -3170,6 +3176,7 @@ nfsrv_openctrl(struct nfsrv_descript *nd, vnode_t vp,
NFSLCK_READACCESS |
NFSLCK_WRITEACCESS);
*rflagsp |= NFSV4OPEN_WRITEDELEGATE;
nfsrv_writedelegcnt++;
} else {
new_deleg->ls_flags =
(NFSLCK_DELEGREAD |
@ -5300,6 +5307,8 @@ nfsrv_checkgetattr(struct nfsrv_descript *nd, vnode_t vp,
NFSCBGETATTR_ATTRBIT(attrbitp, &cbbits);
if (!NFSNONZERO_ATTRBIT(&cbbits))
goto out;
if (nfsrv_writedelegcnt == 0)
goto out;
/*
* Get the lock file structure.