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nfsd41: bound forechannel drc size by memory usage 

By using the requested ca_maxresponsesize_cached * ca_maxresponses to bound
a forechannel drc request size, clients can tailor a session to usage.

For example, an I/O session (READ/WRITE only) can have a much smaller
ca_maxresponsesize_cached (for only WRITE compound responses) and a lot larger
ca_maxresponses to service a large in-flight data window.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
This commit is contained in:
Andy Adamson 2009-08-28 08:45:01 -04:00 committed by J. Bruce Fields
parent a06b1261bd
commit a649637c73
2 changed files with 55 additions and 21 deletions
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68
fs/nfsd/nfs4state.c
View File

@ -414,34 +414,64 @@ gen_sessionid(struct nfsd4_session *ses)
}
/*
* Give the client the number of slots it requests bound by
* NFSD_MAX_SLOTS_PER_SESSION and by nfsd_drc_max_mem.
*
* If we run out of reserved DRC memory we should (up to a point) re-negotiate
* active sessions and reduce their slot usage to make rooom for new
* connections. For now we just fail the create session.
* The protocol defines ca_maxresponssize_cached to include the size of
* the rpc header, but all we need to cache is the data starting after
* the end of the initial SEQUENCE operation--the rest we regenerate
* each time. Therefore we can advertise a ca_maxresponssize_cached
* value that is the number of bytes in our cache plus a few additional
* bytes. In order to stay on the safe side, and not promise more than
* we can cache, those additional bytes must be the minimum possible: 24
* bytes of rpc header (xid through accept state, with AUTH_NULL
* verifier), 12 for the compound header (with zero-length tag), and 44
* for the SEQUENCE op response:
*/
static int set_forechannel_maxreqs(struct nfsd4_channel_attrs *fchan)
#define NFSD_MIN_HDR_SEQ_SZ (24 + 12 + 44)
/*
* Give the client the number of ca_maxresponsesize_cached slots it
* requests, of size bounded by NFSD_SLOT_CACHE_SIZE,
* NFSD_MAX_MEM_PER_SESSION, and nfsd_drc_max_mem. Do not allow more
* than NFSD_MAX_SLOTS_PER_SESSION.
*
* If we run out of reserved DRC memory we should (up to a point)
* re-negotiate active sessions and reduce their slot usage to make
* rooom for new connections. For now we just fail the create session.
*/
static int set_forechannel_drc_size(struct nfsd4_channel_attrs *fchan)
{
int mem;
int mem, size = fchan->maxresp_cached;
if (fchan->maxreqs < 1)
return nfserr_inval;
else if (fchan->maxreqs > NFSD_MAX_SLOTS_PER_SESSION)
fchan->maxreqs = NFSD_MAX_SLOTS_PER_SESSION;
mem = fchan->maxreqs * NFSD_SLOT_CACHE_SIZE;
if (size < NFSD_MIN_HDR_SEQ_SZ)
size = NFSD_MIN_HDR_SEQ_SZ;
size -= NFSD_MIN_HDR_SEQ_SZ;
if (size > NFSD_SLOT_CACHE_SIZE)
size = NFSD_SLOT_CACHE_SIZE;
/* bound the maxreqs by NFSD_MAX_MEM_PER_SESSION */
mem = fchan->maxreqs * size;
if (mem > NFSD_MAX_MEM_PER_SESSION) {
fchan->maxreqs = NFSD_MAX_MEM_PER_SESSION / size;
if (fchan->maxreqs > NFSD_MAX_SLOTS_PER_SESSION)
fchan->maxreqs = NFSD_MAX_SLOTS_PER_SESSION;
mem = fchan->maxreqs * size;
}
spin_lock(&nfsd_drc_lock);
if (mem + nfsd_drc_mem_used > nfsd_drc_max_mem)
mem = ((nfsd_drc_max_mem - nfsd_drc_mem_used) /
NFSD_SLOT_CACHE_SIZE) * NFSD_SLOT_CACHE_SIZE;
/* bound the total session drc memory ussage */
if (mem + nfsd_drc_mem_used > nfsd_drc_max_mem) {
fchan->maxreqs = (nfsd_drc_max_mem - nfsd_drc_mem_used) / size;
mem = fchan->maxreqs * size;
}
nfsd_drc_mem_used += mem;
spin_unlock(&nfsd_drc_lock);
fchan->maxreqs = mem / NFSD_SLOT_CACHE_SIZE;
if (fchan->maxreqs == 0)
return nfserr_resource;
fchan->maxresp_cached = size + NFSD_MIN_HDR_SEQ_SZ;
return 0;
}
@ -466,9 +496,6 @@ static int init_forechannel_attrs(struct svc_rqst *rqstp,
fchan->maxresp_sz = maxcount;
session_fchan->maxresp_sz = fchan->maxresp_sz;
session_fchan->maxresp_cached = NFSD_SLOT_CACHE_SIZE;
fchan->maxresp_cached = session_fchan->maxresp_cached;
/* Use the client's maxops if possible */
if (fchan->maxops > NFSD_MAX_OPS_PER_COMPOUND)
fchan->maxops = NFSD_MAX_OPS_PER_COMPOUND;
@ -478,9 +505,12 @@ static int init_forechannel_attrs(struct svc_rqst *rqstp,
* recover pages from existing sessions. For now fail session
* creation.
*/
status = set_forechannel_maxreqs(fchan);
status = set_forechannel_drc_size(fchan);
session_fchan->maxresp_cached = fchan->maxresp_cached;
session_fchan->maxreqs = fchan->maxreqs;
dprintk("%s status %d\n", __func__, status);
return status;
}

8
include/linux/nfsd/state.h
View File

@ -92,13 +92,17 @@ struct nfs4_cb_conn {
struct rpc_cred * cb_cred;
};
/* Maximum number of slots per session. 128 is useful for long haul TCP */
#define NFSD_MAX_SLOTS_PER_SESSION 128
/* Maximum number of slots per session. 160 is useful for long haul TCP */
#define NFSD_MAX_SLOTS_PER_SESSION 160
/* Maximum number of pages per slot cache entry */
#define NFSD_PAGES_PER_SLOT 1
#define NFSD_SLOT_CACHE_SIZE PAGE_SIZE
/* Maximum number of operations per session compound */
#define NFSD_MAX_OPS_PER_COMPOUND 16
/* Maximum number of NFSD_SLOT_CACHE_SIZE slots per session */
#define NFSD_CACHE_SIZE_SLOTS_PER_SESSION 32
#define NFSD_MAX_MEM_PER_SESSION \
(NFSD_CACHE_SIZE_SLOTS_PER_SESSION * NFSD_SLOT_CACHE_SIZE)
struct nfsd4_cache_entry {
__be32 ce_status;