Hello,
On 04/11/2021 15:46, Kinsella, Ray wrote:
I would guess it - I would say it is related to cache alignment.
Assuming each entry is 8 bytes 😊
Ray K
-----Original Message-----
From: Thomas Monjalon <[email protected]>
Sent: Thursday 4 November 2021 14:12
To: Syam Prasad N Pearson <[email protected]>
Cc: [email protected]; [email protected]; Wang, Yipeng1
<[email protected]>; Gobriel, Sameh <[email protected]>;
Richardson, Bruce <[email protected]>; Medvedkin, Vladimir
<[email protected]>
Subject: Re: [dpdk-dev] Doubt regarding DPDK hash Library
implementation
+Cc hash lib maintainers
01/11/2021 11:55, Syam Prasad N Pearson:
Dear Sir/Madam,
I am a developer trying to get familiar with the DPDK hash library.
I
tried to make and use a hash table successfully.
During the development I came across a variable
/** Number of items per bucket. */
*#define RTE_HASH_BUCKET_ENTRIES 8*
defined inside:
dpdk-20.11.3/dpdk-stable-20.11.3/lib/librte_hash /rte_cuckoo_hash.h
Why does the library take this value as *8*, is there any particular
reason for this? what if it is 16,32... etc.
Yes, RTE_HASH_BUCKET_ENTRIES can be any power of 2.
The reason for choosing 8 is a tradeoff between performance and memory.
When it is equal to 8, the sizeof(struct rte_hash_bucket) equal to
RTE_CACHE_LINE_SIZE, thus, there are no gaps in memory between the hash
buckets due to their alignment.
I am using DPDK 20.11.3 LTS.
Please help.
--
Regards,
Vladimir
