linux-ext4 - Re: [PATCH] ext4: slab caches set to SLAB_MEM

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 16 Nov 2011 10:51:59 -0500
From:	Theodore Tso <tytso@....EDU>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	Theodore Tso <tytso@....edu>, linux-kernel@...r.kernel.org,
	linux-ext4@...r.kernel.org,
	Amit Sahrawat <amit.sahrawat83@...il.com>
Subject: Re: [PATCH] ext4: slab caches set to SLAB_MEM_SPREAD flags.

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

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html