Date: Sat, 16 Jun 2018 12:12:31 -0700 From: bob prohaska <fbsd@www.zefox.net> To: Warner Losh <imp@bsdimp.com> Cc: Mark Millard <marklmi@yahoo.com>, "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org>, "Rodney W. Grimes" <freebsd-rwg@pdx.rh.cn85.dnsmgr.net>, bob prohaska <fbsd@www.zefox.net> Subject: Re: GPT vs MBR for swap devices Message-ID: <20180616191231.GA45514@www.zefox.net> In-Reply-To: <CANCZdfoCA=E=Sh2X6H=Fi-TBkhiTdyzXAkjXr4usa8ie6%2Buo4g@mail.gmail.com> References: <20180614175622.GC35161@www.zefox.net> <201806142110.w5ELAL0N046840@pdx.rh.CN85.dnsmgr.net> <20180615035225.GA37370@www.zefox.net> <CANCZdfoNasSpvEN-y3bzsDfWT=_atfp62AKvdpwK8bUQKi=bgA@mail.gmail.com> <20180615051527.GB37370@www.zefox.net> <834EA7A6-B567-436F-96B2-0C75FACA3FF9@yahoo.com> <20180615154334.GA39777@www.zefox.net> <CANCZdfoCA=E=Sh2X6H=Fi-TBkhiTdyzXAkjXr4usa8ie6%2Buo4g@mail.gmail.com>
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On Fri, Jun 15, 2018 at 09:57:17AM -0600, Warner Losh wrote: > > Right, this is why I was suggesting gstat. It's a direct measure of the > read/write performance of the device with some latency numbers. It will > give the kind of data I'm looking for. Here is a first cut at recording gstat data on r334939 during two -j4 buildworld sessions. The interesting one uses 2 GB of SD flash swap on the boot device and 1 GB of USB flash on the thumb drive hosting the outboard file systems. The readme and log file are at http://www.zefox.net/~fbsd/rpi3/swaptests/ The logging command was gstat -aBd -I 10s > 2gbsdflash_1gbusbflash.log It looks as if something strange happens when swap is placed on two separate interfaces. In the mixed USB/SD case, it appears that the SD flash swap is ignored and the USB flash swap is never very busy (eyeball scan only). The failed buildworld ended at the bootstrap tools stage, swap was on da0b and mmcsd0s3d. It's already known that having all swap on SD flash in two partitions or all swap on USB mechanical disk in one partition works. There is also an RPI2 case with all swap on USB flash in one partition at http://www.zefox.net/~fbsd/rpi2/swaptests/ in case it's of interest. At this stage I don't know what to try next, suggestions are welcome. It would be easy to sample at 1 second rather than ten. Cutting SD flash swap down to 1 or 2 GB is also easy. Likewise, reducing to 1 GB USB flash swap is easy. I have a powered hub so USB things can be added, but that makes the setup more complicated rather than less. Thanks very much for reading, bob prohaska
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