On Thu, Aug 27, 2009 at 12:07 PM, <andros@xxxxxxxxxx> wrote:
> From: Andy Adamson <andros@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> ---
> fs/nfsd/nfs4state.c | 60 +++++++++++++++++++++++++++++++------------
> include/linux/nfsd/state.h | 8 ++++-
> 2 files changed, 49 insertions(+), 19 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index ddfd36f..a691139 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -414,34 +414,60 @@ 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.
> + * 32 bytes of RPC header and 44 bytes of sequence operation response
> + * not included in NFSD_SLOT_CACHE_SIZE
> + * */
> +#define NFSD_MIN_HDR_SEQ_SZ (32 + 44)
> +
> +/*
> + * Give the client the number of ca_maxresponsesize_cached slots it requests
> + * bounded by NFSD_SLOT_CACHE_SIZE, NFSD_MAX_MEM_PER_SESSION and by
> + * nfsd_drc_max_mem. Do not allow more than NFSD_MAX_SLOTS_PER_SESSION.
> + *
> + * The ca_maxresponssize_cached definition includes the size
> + * of the rpc header with the variable length security flavor credential
> + * plus verifier (32 bytes with AUTH_SYS and NULL verifier)
> + * as well as the encoded SEQUENCE operation response (44 bytes)
> + * which are not included in NFSD_SLOT_CACHE_SIZE.
> + * We err on the side of being a bit small when AUTH_SYS/NULL verifier
> + * is not used.
> *
> * 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_maxreqs(struct nfsd4_channel_attrs *fchan)
> +static int set_forechannel_drc_size(struct nfsd4_channel_attrs *fchan)
> {
> - int mem;
> + int mem, size = fchan->maxresp_cached - NFSD_MIN_HDR_SEQ_SZ;
>
> - if (fchan->maxreqs < 1)
> + if (fchan->maxreqs < 1 || size <= 0)
> 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_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;
> + return nfserr_serverfault;
^^^^^^^^^^^^^^^^^^^
This change belongs in patch [PATCH 4/5] nfsd41: replace
nfserr_resource in pure nfs41 responses
-->Andy
> +
> + fchan->maxresp_cached = size + NFSD_MIN_HDR_SEQ_SZ;
> return 0;
> }
>
> @@ -466,9 +492,6 @@ 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 +501,12 @@ 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;
> }
>
> diff --git a/include/linux/nfsd/state.h b/include/linux/nfsd/state.h
> index fb0c404..ff0b771 100644
> --- a/include/linux/nfsd/state.h
> +++ b/include/linux/nfsd/state.h
> @@ -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;
> --
> 1.6.2.5
>
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