Date: Sun, 02 Oct 2011 08:11:45 -0700 From: Xin LI <delphij@delphij.net> To: Olivier Smedts <olivier@gid0.org> Cc: freebsd-fs@freebsd.org, Adrian Chadd <adrian@freebsd.org>, delphij@freebsd.org Subject: Re: is TMPFS still highly experimental? Message-ID: <4E887F31.8000407@delphij.net> In-Reply-To: <CABzXLYOuunKT6pQ3Jpb4J10LHvyKHEuom47s2%2B5D7vXZczYw7A@mail.gmail.com> References: <CAOfDtXMm9K_fbOmvG2gvXxDfKakkgpPt9MLifqDxa4wCibMExg@mail.gmail.com> <alpine.GSO.1.10.1110011122030.882@multics.mit.edu> <CADLo83-s_3H8PbbxOPPxbe0m10U0U5JW-feB294dFs%2BQ3iTWvg@mail.gmail.com> <CAGMYy3ssi%2BkAuufDTHA1z6u7jRrZwRRkCCkcO94GHNGF9Rku_w@mail.gmail.com> <CABzXLYOuunKT6pQ3Jpb4J10LHvyKHEuom47s2%2B5D7vXZczYw7A@mail.gmail.com>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On 10/02/11 03:23, Olivier Smedts wrote: > 2011/10/2 Xin LI <delphij@gmail.com>: >> Hi, >> >> On Sat, Oct 1, 2011 at 8:48 AM, Chris Rees <crees@freebsd.org> >> wrote: >>> I've also not heard of anyone using it with zfs successfully- >>> it tends to shrink rapidly. >> >> I'm quite surprised with this assertion. I use tmpfs on my own >> system and I never see such problem as long as one have >> sufficient swap space. > > The problem here is "sufficient swap space". > > I've got 8G of RAM, and 2G of swap (just in case). When the ZFS > ARC reaches 4G, there's no room for a single byte in tmpfs, even > with 2G swap free and at least 2-3G RAM free. The swap size must be > at least the RAM size if you plan on using ZFS and tmpfs. That's a > problem for me because I'm short on disk space, and there's no > point in having an enormous swap size (hey, minidumps !) when you > already have lots of RAM, which is the case in most ZFS installs. A possible workaround for this might be limiting ARC size? I can't think about any better idea at this point. My personal experience is always have at least RAM sized swap because the system may choose to write in-core data to swap which enables it to discard these memory without expensive swapout in emergency cases. Depending on workload, this could give better responsiveness and frankly I never consider having a few tens of GBs of swap as expensive since large disks are not expensive nowadays... Cheers, - -- Xin LI <delphij@delphij.net> https://www.delphij.net/ FreeBSD - The Power to Serve! Live free or die -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (FreeBSD) iQEcBAEBCAAGBQJOiH8xAAoJEATO+BI/yjfB/BsH/1IpXJioC+R5ZwUBE2mRDP/E rlwGjx138iHFzUjQn7Q8YYmmPhUKiad2fQOIwnErfMOjPUiEVP/CLBya6jQG8g6n wHco8ilIerMSM8i7R1iTbC9gJxte2orxTBrnLkTMr1AcW/MjxpSBL4Z2kzIrZdsx 8bEFCig0tKY5gluM8ZTBaMK+yVEFV+ff6PHiHu//XcnG03CFqiu9V4HMhvrXCTcB QBDl+/8+PdLPWEDHLzSW51te1YEoF/xDkDkHu7UtTX3egEkiDeZ2uCmazgWFu/Xw TPMRiXUfYklDpT+rMbRH44CN5VeEWhOyZRDyr/pGOzjylAe2ShFGNxpua+KpLJI= =0mDY -----END PGP SIGNATURE-----
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