From: Theodore Tso <tytso@MIT.EDU>
To: Namjae Jeon <linkinjeon@gmail.com>
Cc: Theodore Tso <tytso@mit.edu>,
linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org,
Amit Sahrawat <amit.sahrawat83@gmail.com>
Subject: Re: [PATCH] ext4: slab caches set to SLAB_MEM_SPREAD flags.
Date: Wed, 16 Nov 2011 10:51:59 -0500 [thread overview]
Message-ID: <47270FB7-96AC-4F41-98D3-9AD469080DBE@mit.edu> (raw)
In-Reply-To: <1321455848-1929-1-git-send-email-linkinjeon@gmail.com>
On Nov 16, 2011, at 10:04 AM, Namjae Jeon wrote:
> If slab caches set to SLAB_MEM_SPREAD flags, The allocation is spread evenly over all the memory nodes instead of favoring allocation on the node local to current cpu.
And why do you think this is a good thing? For mballoc in particular, the data structures are used immediately and then freed immediately --- on the local node, so using a non-local memory just makes things worse in a NUMA system.
For the pageio, they are used immediately, and may end up getting freed on the same CPU if the I/O interrupt (and hence competion callbacks) happen on the same CPU that they are submitted on….
Regards,
-- Ted
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next prev parent reply other threads:[~2011-11-16 15:52 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-16 15:04 [PATCH] ext4: slab caches set to SLAB_MEM_SPREAD flags Namjae Jeon
2011-11-16 15:51 ` Theodore Tso [this message]
2011-11-16 21:52 ` David Rientjes
2011-11-17 5:11 ` Amit Sahrawat
2011-11-17 5:35 ` NamJae Jeon
2011-11-17 15:11 ` Theodore Tso
2011-11-17 21:34 ` Theodore Tso
2011-11-19 13:52 ` NamJae Jeon
2011-11-19 14:42 ` Theodore Tso
2011-11-19 15:40 ` NamJae Jeon
2011-11-19 21:14 ` Theodore Tso
2011-11-19 22:22 ` NamJae Jeon
2011-11-19 21:06 ` Theodore Tso
2011-11-19 22:16 ` NamJae Jeon
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