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From: Thomas Monjalon <thomas@monjalon.net>
To: "Medvedkin, Vladimir" <vladimir.medvedkin@intel.com>
Cc: "Kinsella, Ray" <ray.kinsella@intel.com>,
	Syam Prasad N Pearson <syam.pearson@gadgeon.com>,
	"users@dpdk.org" <users@dpdk.org>, "dev@dpdk.org" <dev@dpdk.org>,
	"Wang, Yipeng1" <yipeng1.wang@intel.com>,
	"Gobriel, Sameh" <sameh.gobriel@intel.com>,
	"Richardson, Bruce" <bruce.richardson@intel.com>
Subject: Re: [dpdk-dev] Doubt regarding DPDK hash Library implementation
Date: Thu, 04 Nov 2021 17:49:51 +0100
Message-ID: <3060108.LiUVKm96O0@thomas> (raw)
In-Reply-To: <6c1c908e-6a9a-c50d-0fa3-be61770ef97c@intel.com>

04/11/2021 17:39, Medvedkin, Vladimir:
> >> 01/11/2021 11:55, Syam Prasad N Pearson:
> >>> /** 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.

That's a good comment to add in the code.



  reply	other threads:[~2021-11-04 16:50 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-01 10:55 Syam Prasad N Pearson
2021-11-04 14:11 ` [dpdk-dev] " Thomas Monjalon
2021-11-04 14:46   ` Kinsella, Ray
2021-11-04 16:39     ` Medvedkin, Vladimir
2021-11-04 16:49       ` Thomas Monjalon [this message]
2021-11-06 23:23         ` Syam Prasad N Pearson

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