freebsd-skq/sys/nfs/nfs_fha.h
mav c2a28dc66d Improve FHA locality control for NFS read/write requests.
This change adds two new tunables, allowing to control serialization for
read and write NFS requests separately.  It does not change the default
behavior since there are too many factors to consider, but gives additional
space for further experiments and tuning.

The main motivation for this change is very low write speed in case of ZFS
with sync=always or when NFS clients requests sychronous operation, when
every separate request has to be written/flushed to ZIL, and requests are
processed one at a time.  Setting vfs.nfsd.fha.write=0 in that case allows
to increase ZIL throughput by several times by coalescing writes and cache
flushes.  There is a worry that doing it may increase data fragmentation
on disks, but I suppose it should not happen for pool with SLOG.

MFC after:	1 week
Sponsored by:	iXsystems, Inc.
2017-07-31 15:23:19 +00:00

121 lines
4.0 KiB
C

/*-
* Copyright (c) 2008 Isilon Inc http://www.isilon.com/
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/* $FreeBSD$ */
#ifndef _NFS_FHA_H
#define _NFS_FHA_H 1
#ifdef _KERNEL
/* Sysctl defaults. */
#define FHA_DEF_ENABLE 1
#define FHA_DEF_READ 1
#define FHA_DEF_WRITE 1
#define FHA_DEF_BIN_SHIFT 22 /* 4MB */
#define FHA_DEF_MAX_NFSDS_PER_FH 8
#define FHA_DEF_MAX_REQS_PER_NFSD 0 /* Unlimited */
#define FHA_HASH_SIZE 251
struct fha_ctls {
int enable;
int read;
int write;
uint32_t bin_shift;
uint32_t max_nfsds_per_fh;
uint32_t max_reqs_per_nfsd;
};
/*
* These are the entries in the filehandle hash. They talk about a specific
* file, requests against which are being handled by one or more nfsds. We
* keep a chain of nfsds against the file. We only have more than one if reads
* are ongoing, and then only if the reads affect disparate regions of the
* file.
*
* In general, we want to assign a new request to an existing nfsd if it is
* going to contend with work happening already on that nfsd, or if the
* operation is a read and the nfsd is already handling a proximate read. We
* do this to avoid jumping around in the read stream unnecessarily, and to
* avoid contention between threads over single files.
*/
struct fha_hash_entry {
struct mtx *mtx;
LIST_ENTRY(fha_hash_entry) link;
u_int64_t fh;
u_int32_t num_rw;
u_int32_t num_exclusive;
u_int8_t num_threads;
struct svcthread_list threads;
};
LIST_HEAD(fha_hash_entry_list, fha_hash_entry);
struct fha_hash_slot {
struct fha_hash_entry_list list;
struct mtx mtx;
};
/* A structure used for passing around data internally. */
struct fha_info {
u_int64_t fh;
off_t offset;
int locktype;
int read;
int write;
};
struct fha_callbacks {
rpcproc_t (*get_procnum)(rpcproc_t procnum);
int (*realign)(struct mbuf **mb, int malloc_flags);
int (*get_fh)(uint64_t *fh, int v3, struct mbuf **md, caddr_t *dpos);
int (*is_read)(rpcproc_t procnum);
int (*is_write)(rpcproc_t procnum);
int (*get_offset)(struct mbuf **md, caddr_t *dpos, int v3, struct
fha_info *info);
int (*no_offset)(rpcproc_t procnum);
void (*set_locktype)(rpcproc_t procnum, struct fha_info *info);
int (*fhe_stats_sysctl)(SYSCTL_HANDLER_ARGS);
};
struct fha_params {
struct fha_hash_slot fha_hash[FHA_HASH_SIZE];
struct sysctl_ctx_list sysctl_ctx;
struct sysctl_oid *sysctl_tree;
struct fha_ctls ctls;
struct fha_callbacks callbacks;
char server_name[32];
SVCPOOL **pool;
};
void fha_nd_complete(SVCTHREAD *, struct svc_req *);
SVCTHREAD *fha_assign(SVCTHREAD *, struct svc_req *, struct fha_params *);
void fha_init(struct fha_params *softc);
void fha_uninit(struct fha_params *softc);
int fhe_stats_sysctl(SYSCTL_HANDLER_ARGS, struct fha_params *softc);
#endif /* _KERNEL */
#endif /* _NFS_FHA_H_ */