Date: Fri, 9 Nov 2012 14:37:46 +0100 From: Achim Patzner <ap@bnc.net> To: David <turbolad995@yahoo.co.uk> Cc: freebsd-performance@freebsd.org Subject: Re: Compressed RAM disk swap space Message-ID: <C9896033-7D0B-47AB-9202-E29378A0D64D@bnc.net> In-Reply-To: <509CF81F.7090803@yahoo.co.uk> References: <509CF81F.7090803@yahoo.co.uk>
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Am 09.11.2012 um 13:33 schrieb David <turbolad995@yahoo.co.uk>: > Hi, I have tried something which actually boosts performance It doesn't; it just moves the load from one limited resource (RAM) to = another one (CPU cycles), adding its own overhead on the way. It just = means that your machine got too large an engine for your tires. Save on = CPU power and get more RAM next time. > : a compressed RAM disk used as swap space. It nearly sounds as good as "hey, we've got virtual memory, let's = generate an incredibly large RAM disk". To me it sounds like investing = into sovereign debt of your home country and paying your interest rate = with your own increased taxes. Why swap into RAM if your process could = use it as well? About the cost of compression: This idea was already annoying decades = ago (doesn't anyone remember those "RAM extenders" for MS-DOS that gave = you "more RAM than your computer contains"?) when software suddenly got = inexplicably slow (until you found the driver chewing on its own tail by = trying to decompress itself) and was one of the reasons I moved to SCO = and BSD/386. Achim
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