DPDK patches and discussions
 help / color / mirror / Atom feed
From: "Yeddula, Avinash" <ayeddula@ciena.com>
To: "Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>,
	"dev@dpdk.org" <dev@dpdk.org>, "Bly, Mike" <mbly@ciena.com>
Subject: Re: [dpdk-dev] DPDK hash function related question
Date: Mon, 12 Oct 2015 13:03:16 -0400	[thread overview]
Message-ID: <A1E50D8AD6310E47A6C10F075AEDC022037A46312D@ONWVEXCHMB01.ciena.com> (raw)
In-Reply-To: <3EB4FA525960D640B5BDFFD6A3D89126478D64A1@IRSMSX108.ger.corp.intel.com>

Hi Cristian,
I have configured the hash function and it compile fine with "warnings". Since librte_hash vs librte_table is 32bit vs 64bit.

librte_hash library :
/** Type of function that can be used for calculating the hash value. */
typedef uint32_t (*rte_hash_function)(const void *key, uint32_t key_len, uint32_t init_val);

librte_table library:
typedef uint64_t (*rte_table_hash_op_hash) (void *key,	uint32_t key_size, uint64_t seed);

I could use one of these hash functions. This is one option, but our first priority is  to use crc hash or cukoo hash.
https://github.com/scylladb/dpdk/blob/master/examples/ip_pipeline/pipeline/hash_func.h

We do not want to have those warning in our code. What do you suggest ?

Thanks
-Avinash

-----Original Message-----
From: Dumitrescu, Cristian [mailto:cristian.dumitrescu@intel.com] 
Sent: Tuesday, September 22, 2015 3:05 AM
To: Yeddula, Avinash; dev@dpdk.org; Bly, Mike
Subject: RE: DPDK hash function related question

Hi Avinash,

Yes, the hash function is configurable.

Are you using a DPDK release older than 2.1? In DPDK we moved away from test_hash to CRC-based hashes. Please take a look at DPDK release 2.1 examples/ip_pipeline application: in pipeline_flow_classification_be.c, we use CRC-based hash functions defined in file hash_func.h from the same folder.

Regards,
Cristian

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Yeddula, Avinash
> Sent: Tuesday, September 22, 2015 1:34 AM
> To: dev@dpdk.org; Bly, Mike
> Subject: [dpdk-dev] DPDK hash function related question
> 
> Hello All,
> 
> I'm DPDK extensible bucket hash in the rte_table library of packet 
> framework. My question is related to the actual hash function that 
> computes the hash signature.
> 
> All the available examples have initialized it to test_hash.   I do not see any
> hash function available in rte_table library , that computes the 
> actual signature
> 
> 
> 
> struct rte_table_hash_ext_params   hash_table_params = {
> 
>     .key_size = TABLE_ENTRY_KEY_SIZE,
> 
>     .n_keys = TABLE_MAX_SIZE,
> 
>     .n_buckets = TABLE_MAX_BUCKET_COUNT,
> 
>     .n_buckets_ext = TABLE_MAX_EXT_BUCKET_COUNT,
> 
>     .f_hash = test_hash,
> 
>     .seed = 0,
> 
>     .signature_offset = 0;
> 
>     .key_offset = __builtin_offsetof(struct metadata_t, tbl_key),
> 
> };
> 
> 
> 
> So, I wanted to use hash functions from DPDK rte_hash library. This is 
> what I'm doing and looking at the code this looks ok to me.
> 
> I'm at least a week or 2 away from testing this part of the code. I 
> wanted to confirm that, there is no fundamental flaw in using the DPDK 
> rte_hash library and rte_table library like this. Could someone confirm this please ?
> 
> 
> 
> #define DEFAULT_HASH_FUNC rte_hash_crc
> 
> 
> 
> struct rte_table_hash_ext_params   hash_table_params = {
> 
>     .key_size = TABLE_ENTRY_KEY_SIZE,
> 
>     .n_keys = TABLE_MAX_SIZE,
> 
>     .n_buckets = TABLE_MAX_BUCKET_COUNT,
> 
>     .n_buckets_ext = TABLE_MAX_EXT_BUCKET_COUNT,
> 
>     .f_hash = DEFAULT_HASH_FUNC ,
> 
>     .seed = 0,
> 
>     .signature_offset = 0;
> 
>     .key_offset = __builtin_offsetof(struct metadata_t, tbl_key),
> 
> };
> 
> 
> 
> Thanks
> 
> -Avinash
> 

  parent reply	other threads:[~2015-10-12 17:03 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-21 22:34 Yeddula, Avinash
2015-09-22 10:05 ` Dumitrescu, Cristian
2015-09-22 13:40   ` Thomas Monjalon
2015-09-23 12:47     ` Dumitrescu, Cristian
2015-10-12 17:03   ` Yeddula, Avinash [this message]
2015-10-13  8:05     ` De Lara Guarch, Pablo
2015-10-13 11:44     ` Dumitrescu, Cristian

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=A1E50D8AD6310E47A6C10F075AEDC022037A46312D@ONWVEXCHMB01.ciena.com \
    --to=ayeddula@ciena.com \
    --cc=cristian.dumitrescu@intel.com \
    --cc=dev@dpdk.org \
    --cc=mbly@ciena.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).