Date: Tue, 8 Feb 2011 10:53:44 -0800 From: "Robert N. M. Watson" <rwatson@FreeBSD.org> To: Alan Cox <alc@rice.edu> Cc: alc@freebsd.org, freebsd-hackers@freebsd.org, Ivan Voras <ivoras@freebsd.org> Subject: Re: Analyzing wired memory? Message-ID: <709DC06E-11E8-4B92-8623-0EB8C835B28B@FreeBSD.org> In-Reply-To: <4D518D82.4090102@rice.edu> References: <iirce4$urj$1@dough.gmane.org> <AANLkTikNw4G7MDHwCAmxfzFGUBxQb1S9pUjTM_-g3K%2By@mail.gmail.com> <alpine.BSF.2.00.1102081825370.12092@fledge.watson.org> <4D518D82.4090102@rice.edu>
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On 8 Feb 2011, at 10:37, Alan Cox wrote: >> John and I have occasionally talked about making procstat -v work on = the kernel; conceivably it could also export a wired page count for = mappings where it makes sense. Ideally procstat would drill in a bit = and allow you to see things at least at the granularty of "this page = range was allocated to UMA". >=20 > I would certainly have found this useful on a few occasions, and would = gladly help out with implementing it. For example, it would help us in = understanding the kmem_map fragmentation caused by ZFS. That said, I'm = not sure how you will represent the case where UMA allocates physical = memory directly and uses the direct map to access it. I agree -- in some sense, my proposal is related to, but somewhat = orthogonal to, the problem Ivan is running into. We could also have a more detailed but UMA-specific inspection tool; I = have a uma dumping tool in src/tools somewhere that dumps zone = information, buckets, etc, for UMA types. I've used this in the past to = explore mbuf alloc/free behaviour, multi-CPU imbalances in allocation, = over-caching, etc. It may be time to revisit that, decide how to make it = a bit more user/developer-friendly, and make it a formally supported = tool as part of vmstat (which involves adding some new sysctls as well). Robert
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