From: Sasha Levin <levinsasha928@gmail.com>
To: Josh Triplett <josh@joshtriplett.org>
Cc: torvalds@linux-foundation.org, tj@kernel.org,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, paul.gortmaker@windriver.com,
davem@davemloft.net, rostedt@goodmis.org, mingo@elte.hu,
ebiederm@xmission.com, aarcange@redhat.com, ericvh@gmail.com,
netdev@vger.kernel.org, eric.dumazet@gmail.com,
mathieu.desnoyers@efficios.com
Subject: Re: [RFC v3 1/7] hashtable: introduce a small and naive hashtable
Date: Tue, 07 Aug 2012 11:49:41 +0200 [thread overview]
Message-ID: <5020E4B5.4040702@gmail.com> (raw)
In-Reply-To: <20120807025520.GA3823@leaf>
On 08/07/2012 04:55 AM, Josh Triplett wrote:
> On Tue, Aug 07, 2012 at 02:45:10AM +0200, Sasha Levin wrote:
>> +/**
>> + * hash_add - add an object to a hashtable
>> + * @hashtable: hashtable to add to
>> + * @bits: bit count used for hashing
>> + * @node: the &struct hlist_node of the object to be added
>> + * @key: the key of the object to be added
>> + */
>> +#define hash_add(hashtable, bits, node, key) \
>> + hlist_add_head(node, &hashtable[hash_min(key, bits)]);
>
> Any particular reason to make this a macro rather than a static inline?
Yes. As Eric Dumazet pointed out, hash_64() is slower than hash_32() so we should be calling hash_32() if possible (if key size is 32bits long).
This way we can call hash_min() without knowing the key size. See also the definition of hash_min() above.
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WARNING: multiple messages have this Message-ID (diff)
From: Sasha Levin <levinsasha928@gmail.com>
To: Josh Triplett <josh@joshtriplett.org>
Cc: torvalds@linux-foundation.org, tj@kernel.org,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, paul.gortmaker@windriver.com,
davem@davemloft.net, rostedt@goodmis.org, mingo@elte.hu,
ebiederm@xmission.com, aarcange@redhat.com, ericvh@gmail.com,
netdev@vger.kernel.org, eric.dumazet@gmail.com,
mathieu.desnoyers@efficios.com
Subject: Re: [RFC v3 1/7] hashtable: introduce a small and naive hashtable
Date: Tue, 07 Aug 2012 11:49:41 +0200 [thread overview]
Message-ID: <5020E4B5.4040702@gmail.com> (raw)
In-Reply-To: <20120807025520.GA3823@leaf>
On 08/07/2012 04:55 AM, Josh Triplett wrote:
> On Tue, Aug 07, 2012 at 02:45:10AM +0200, Sasha Levin wrote:
>> +/**
>> + * hash_add - add an object to a hashtable
>> + * @hashtable: hashtable to add to
>> + * @bits: bit count used for hashing
>> + * @node: the &struct hlist_node of the object to be added
>> + * @key: the key of the object to be added
>> + */
>> +#define hash_add(hashtable, bits, node, key) \
>> + hlist_add_head(node, &hashtable[hash_min(key, bits)]);
>
> Any particular reason to make this a macro rather than a static inline?
Yes. As Eric Dumazet pointed out, hash_64() is slower than hash_32() so we should be calling hash_32() if possible (if key size is 32bits long).
This way we can call hash_min() without knowing the key size. See also the definition of hash_min() above.
next prev parent reply other threads:[~2012-08-07 9:49 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-07 0:45 [RFC v3 0/7] generic hashtable implementation Sasha Levin
2012-08-07 0:45 ` Sasha Levin
2012-08-07 0:45 ` [RFC v3 1/7] hashtable: introduce a small and naive hashtable Sasha Levin
2012-08-07 0:45 ` Sasha Levin
2012-08-07 1:19 ` Joe Perches
2012-08-07 1:19 ` Joe Perches
2012-08-07 1:48 ` Li Wei
2012-08-07 1:48 ` Li Wei
2012-08-07 1:54 ` Sasha Levin
2012-08-07 1:54 ` Sasha Levin
2012-08-07 2:55 ` Josh Triplett
2012-08-07 2:55 ` Josh Triplett
2012-08-07 9:49 ` Sasha Levin [this message]
2012-08-07 9:49 ` Sasha Levin
2012-08-07 0:45 ` [RFC v3 2/7] user_ns: use new hashtable implementation Sasha Levin
2012-08-07 0:45 ` Sasha Levin
2012-08-07 0:45 ` [RFC v3 3/7] mm,ksm: " Sasha Levin
2012-08-07 0:45 ` Sasha Levin
2012-08-07 0:45 ` [RFC v3 4/7] workqueue: " Sasha Levin
2012-08-07 0:45 ` Sasha Levin
2012-08-07 0:45 ` Sasha Levin
2012-08-07 0:45 ` Sasha Levin
2012-08-07 1:19 ` Joe Perches
2012-08-07 1:19 ` Joe Perches
2012-08-07 0:45 ` [RFC v3 5/7] mm/huge_memory: " Sasha Levin
2012-08-07 0:45 ` Sasha Levin
2012-08-07 0:45 ` [RFC v3 6/7] tracepoint: " Sasha Levin
2012-08-07 0:45 ` Sasha Levin
2012-08-07 0:45 ` [RFC v3 7/7] net,9p: " Sasha Levin
2012-08-07 0:45 ` Sasha Levin
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