From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by dpdk.org (Postfix) with ESMTP id D86677E9D for ; Mon, 10 Nov 2014 16:04:12 +0100 (CET) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga103.fm.intel.com with ESMTP; 10 Nov 2014 07:06:47 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,353,1413270000"; d="scan'208";a="619995376" Received: from bricha3-mobl3.ger.corp.intel.com ([10.243.20.42]) by fmsmga001.fm.intel.com with SMTP; 10 Nov 2014 07:13:09 -0800 Received: by (sSMTP sendmail emulation); Mon, 10 Nov 2014 15:13:08 +0025 Date: Mon, 10 Nov 2014 15:13:08 +0000 From: Bruce Richardson To: Qinglai Xiao Message-ID: <20141110151308.GC12532@bricha3-MOBL3> References: <1415630642-3905-1-git-send-email-jigsaw@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1415630642-3905-1-git-send-email-jigsaw@gmail.com> Organization: Intel Shannon Ltd. User-Agent: Mutt/1.5.23 (2014-03-12) Cc: dev@dpdk.org Subject: Re: [dpdk-dev] [PATCH v3] Add in_flight_bitmask so as to use full 32 bits of tag. X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Nov 2014 15:04:14 -0000 On Mon, Nov 10, 2014 at 04:44:02PM +0200, Qinglai Xiao wrote: > With introduction of in_flight_bitmask, the whole 32 bits of tag can be > used. Further more, this patch fixed the integer overflow when finding > the matched tags. > The maximum number workers is now defined as 64, which is length of > double-word. The link between number of workers and RTE_MAX_LCORE is > now removed. Compile time check is added to ensure the > RTE_DISTRIB_MAX_WORKERS is less than or equal to size of double-word. > > Signed-off-by: Qinglai Xiao Looks good to me. Just before I ack this, have you checked to see if there is any performance impact? /Bruce > --- > lib/librte_distributor/rte_distributor.c | 64 ++++++++++++++++++++++-------- > lib/librte_distributor/rte_distributor.h | 4 ++ > 2 files changed, 51 insertions(+), 17 deletions(-) > > diff --git a/lib/librte_distributor/rte_distributor.c b/lib/librte_distributor/rte_distributor.c > index 3dfec4a..2c5d61c 100644 > --- a/lib/librte_distributor/rte_distributor.c > +++ b/lib/librte_distributor/rte_distributor.c > @@ -62,6 +62,13 @@ > #define RTE_DISTRIB_RETURNS_MASK (RTE_DISTRIB_MAX_RETURNS - 1) > > /** > + * Maximum number of workers allowed. > + * Be aware of increasing the limit, becaus it is limited by how we track > + * in-flight tags. See @in_flight_bitmask and @rte_distributor_process > + */ > +#define RTE_DISTRIB_MAX_WORKERS 64 > + > +/** > * Buffer structure used to pass the pointer data between cores. This is cache > * line aligned, but to improve performance and prevent adjacent cache-line > * prefetches of buffers for other workers, e.g. when worker 1's buffer is on > @@ -91,11 +98,17 @@ struct rte_distributor { > char name[RTE_DISTRIBUTOR_NAMESIZE]; /**< Name of the ring. */ > unsigned num_workers; /**< Number of workers polling */ > > - uint32_t in_flight_tags[RTE_MAX_LCORE]; > - /**< Tracks the tag being processed per core, 0 == no pkt */ > - struct rte_distributor_backlog backlog[RTE_MAX_LCORE]; > + uint32_t in_flight_tags[RTE_DISTRIB_MAX_WORKERS]; > + /**< Tracks the tag being processed per core */ > + uint64_t in_flight_bitmask; > + /**< on/off bits for in-flight tags. > + * Note that if RTE_DISTRIB_MAX_WORKERS is larger than 64 then > + * the bitmask has to expand. > + */ > + > + struct rte_distributor_backlog backlog[RTE_DISTRIB_MAX_WORKERS]; > > - union rte_distributor_buffer bufs[RTE_MAX_LCORE]; > + union rte_distributor_buffer bufs[RTE_DISTRIB_MAX_WORKERS]; > > struct rte_distributor_returned_pkts returns; > }; > @@ -189,6 +202,7 @@ static inline void > handle_worker_shutdown(struct rte_distributor *d, unsigned wkr) > { > d->in_flight_tags[wkr] = 0; > + d->in_flight_bitmask &= ~(1UL << wkr); > d->bufs[wkr].bufptr64 = 0; > if (unlikely(d->backlog[wkr].count != 0)) { > /* On return of a packet, we need to move the > @@ -211,7 +225,10 @@ handle_worker_shutdown(struct rte_distributor *d, unsigned wkr) > pkts[i] = (void *)((uintptr_t)(bl->pkts[idx] >> > RTE_DISTRIB_FLAG_BITS)); > } > - /* recursive call */ > + /* recursive call. > + * Note that the tags were set before first level call > + * to rte_distributor_process. > + */ > rte_distributor_process(d, pkts, i); > bl->count = bl->start = 0; > } > @@ -242,6 +259,7 @@ process_returns(struct rte_distributor *d) > else { > d->bufs[wkr].bufptr64 = RTE_DISTRIB_GET_BUF; > d->in_flight_tags[wkr] = 0; > + d->in_flight_bitmask &= ~(1UL << wkr); > } > oldbuf = data >> RTE_DISTRIB_FLAG_BITS; > } else if (data & RTE_DISTRIB_RETURN_BUF) { > @@ -284,14 +302,18 @@ rte_distributor_process(struct rte_distributor *d, > next_value = (((int64_t)(uintptr_t)next_mb) > << RTE_DISTRIB_FLAG_BITS); > /* > - * Set the low bit on the tag, so we can guarantee that > - * we never store a tag value of zero. That means we can > - * use the zero-value to indicate that no packet is > - * being processed by a worker. > + * User is advocated to set tag vaue for each > + * mbuf before calling rte_distributor_process. > + * User defined tags are used to identify flows, > + * or sessions. > */ > - new_tag = (next_mb->hash.usr | 1); > + new_tag = next_mb->hash.usr; > > - uint32_t match = 0; > + /* > + * Note that if RTE_DISTRIB_MAX_WORKERS is larger than 64 > + * then the size of match has to be expanded. > + */ > + uint64_t match = 0; > unsigned i; > /* > * to scan for a match use "xor" and "not" to get a 0/1 > @@ -303,9 +325,12 @@ rte_distributor_process(struct rte_distributor *d, > match |= (!(d->in_flight_tags[i] ^ new_tag) > << i); > > + /* Only turned-on bits are considered as match */ > + match &= d->in_flight_bitmask; > + > if (match) { > next_mb = NULL; > - unsigned worker = __builtin_ctz(match); > + unsigned worker = __builtin_ctzl(match); > if (add_to_backlog(&d->backlog[worker], > next_value) < 0) > next_idx--; > @@ -322,6 +347,7 @@ rte_distributor_process(struct rte_distributor *d, > else { > d->bufs[wkr].bufptr64 = next_value; > d->in_flight_tags[wkr] = new_tag; > + d->in_flight_bitmask |= (1UL << wkr); > next_mb = NULL; > } > oldbuf = data >> RTE_DISTRIB_FLAG_BITS; > @@ -379,11 +405,13 @@ rte_distributor_returned_pkts(struct rte_distributor *d, > static inline unsigned > total_outstanding(const struct rte_distributor *d) > { > - unsigned wkr, total_outstanding = 0; > + unsigned wkr, total_outstanding; > + > + total_outstanding = __builtin_popcountl(d->in_flight_bitmask); > > for (wkr = 0; wkr < d->num_workers; wkr++) > - total_outstanding += d->backlog[wkr].count + > - !!(d->in_flight_tags[wkr]); > + total_outstanding += d->backlog[wkr].count; > + > return total_outstanding; > } > > @@ -423,9 +451,11 @@ rte_distributor_create(const char *name, > > /* compilation-time checks */ > RTE_BUILD_BUG_ON((sizeof(*d) & CACHE_LINE_MASK) != 0); > - RTE_BUILD_BUG_ON((RTE_MAX_LCORE & 7) != 0); > + RTE_BUILD_BUG_ON((RTE_DISTRIB_MAX_WORKERS & 7) != 0); > + RTE_BUILD_BUG_ON(RTE_DISTRIB_MAX_WORKERS > > + sizeof(d->in_flight_bitmask) * CHAR_BIT); > > - if (name == NULL || num_workers >= RTE_MAX_LCORE) { > + if (name == NULL || num_workers >= RTE_DISTRIB_MAX_WORKERS) { > rte_errno = EINVAL; > return NULL; > } > diff --git a/lib/librte_distributor/rte_distributor.h b/lib/librte_distributor/rte_distributor.h > index ec0d74a..cc1d559 100644 > --- a/lib/librte_distributor/rte_distributor.h > +++ b/lib/librte_distributor/rte_distributor.h > @@ -88,6 +88,10 @@ rte_distributor_create(const char *name, unsigned socket_id, > * packets. The distributor will ensure that no two packets that have the > * same flow id, or tag, in the mbuf will be procesed at the same time. > * > + * The user is advocated to set tag for each mbuf before calling this function. > + * If user doesn't set the tag, the tag value can be various values depending on > + * driver implementation and configuration. > + * > * This is not multi-thread safe and should only be called on a single lcore. > * > * @param d > -- > 1.7.1 >