Sorry about the delay. The number 32 is not really a CACHE_LINE_SIZE but since __builtin_clz returns the number of leading 0's before the most significant set bit in a 32 bit number (entry_size is uint32_t), I subtract that number from 32 to get the number of trailing bits after the most significant set bit. This will be the separation in my data_mem regions.
-----Original Message----- From: Neil Horman [mailto:nhor...@tuxdriver.com] Sent: Thursday, September 25, 2014 3:22 AM To: Saha, Avik (AWS) Cc: dev at dpdk.org Subject: Re: [dpdk-dev] [PATCH] Fix for LRU corrupted returns On Thu, Sep 25, 2014 at 07:46:16AM +0000, Saha, Avik (AWS) wrote: > This is a patch to a problem that I have faced (described in the thread) and > this works for me. > > 1) Since the data_size_shl was getting its value from the key_size, the > table data entries were being corrupted when the calculation to shift the > number of bits was being made based on the key_size (according to the > document the key_size and entry_size are independently configurable) - With > this fix, we get the MSB that is set in entry_size (also removes the > constraint of this having to be a power of 2 - not entirely sure if this was > the reason the constraint was kept though) > 2) The document does not say that the entry_size needs to be a power of > 2 and this was failing silently when I was trying to bring my application up. > > diff --git a/DPDK/lib/librte_table/rte_table_hash_lru.c > b/DPDK/lib/librte_table/rte_table_hash_lru.c > index d1a4984..4ec9aa4 100644 > --- a/DPDK/lib/librte_table/rte_table_hash_lru.c > +++ b/DPDK/lib/librte_table/rte_table_hash_lru.c > @@ -153,8 +153,10 @@ rte_table_hash_lru_create(void *params, int socket_id, > uint32_t entry_size) > uint32_t i; > > /* Check input parameters */ > - if ((check_params_create(p) != 0) || > - (!rte_is_power_of_2(entry_size)) || > + // Commenting out the power of 2 check on the entry_size since the > + // Programmers Guide does not call this out and we are going to handle > + // the data_size_shl of the table later on (Line 197) Please remove the reference to Line 197 here. Thats not going to remain accurate for very long. > + if ((check_params_create(p) != 0) || > ((sizeof(struct rte_table_hash) % CACHE_LINE_SIZE) != 0) || > (sizeof(struct bucket) != (CACHE_LINE_SIZE / 2))) { > return NULL; > @@ -192,7 +194,7 @@ rte_table_hash_lru_create(void *params, int socket_id, > uint32_t entry_size) > /* Internal */ > t->bucket_mask = t->n_buckets - 1; > t->key_size_shl = __builtin_ctzl(p->key_size); > - t->data_size_shl = __builtin_ctzl(p->key_size); > + t->data_size_shl = 32 - (__builtin_clz(entry_size)); I presume the 32 value here is a cache line size? That should be replaced with CACHE_LINE_SIZE...Though looking at it, that doesn't seem sufficient. Seems like we need a eal abstraction to dynamically tell us what the cache line size is (we can read it from /proc/cpuinfo in linux, not sure about bsd). Neil