Re: XO-1.75 RAM [Devel Digest, Vol 62, Issue 25]
-- Message: 4 Date: Thu, 14 Apr 2011 10:36:10 +1000 From: Sridhar Dhanapalan srid...@laptop.org.au Subject: Re: XO-1.75 RAM To: mi...@bga.com Cc: OLPC Devel devel@lists.laptop.org Message-ID: BANLkTi=_aasxf7++bmxoysaxvmxga4p...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 On 14 April 2011 06:16, Mikus Grinbergs mi...@bga.com wrote: Might 1GB of RAM ?become a performance bottleneck? I myself am skeptical of efforts to use the OLPC where a desktop system might be more effective. ?I've run various large applications on an XO-1.5 system, and have not myself experienced memory shortage. Unless the RAM chips on the XO-1.75 are socketed (and thus easily replaceable), it seems to me that it would be easier to add swap space (rather than RAM) to those systems used to run particularly memory-hungry applications (such as video editing). Flash storage is mush slower than spinning hard drives and wears out far more quickly. I don't think using flash for swap is a good idea. For what it worths I have the same SDcard on the XO-1 with more than 1500 hours of swap use of a 256MB partition, with no problem so far. On the XO-1.5 and its 1GB RAM a rarely see any swap use at all. If anything I would rather see the extra cost towards a proper small SSD to replace SDcards, than extra RAM ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: XO-1.75 RAM
On Thu, Apr 14, 2011 at 12:01:47AM -0700, Yioryos Asprobounitis wrote: For what it worths I have the same SDcard on the XO-1 with more than 1500 hours of swap use of a 256MB partition, with no problem so far. Cool. What was the unit cost of the SD card, what size was it, and how many writes were made over those 1500 hours to the SD card as a whole? (... not just the swap partition, since endurance of the card relates to total writes to the card). -- James Cameron http://quozl.linux.org.au/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: XO-1.75 RAM
--- On Thu, 4/14/11, James Cameron qu...@laptop.org wrote: From: James Cameron qu...@laptop.org Subject: Re: XO-1.75 RAM To: Yioryos Asprobounitis mavrot...@yahoo.com Cc: devel@lists.laptop.org Date: Thursday, April 14, 2011, 3:33 AM On Thu, Apr 14, 2011 at 12:01:47AM -0700, Yioryos Asprobounitis wrote: For what it worths I have the same SDcard on the XO-1 with more than 1500 hours of swap use of a 256MB partition, with no problem so far. Cool. What was the unit cost of the SD card, what size was it, That was/is a $15 Transcend 4GB class 6 card that not only can have 5 erase blocks open but also has an impressive random w/r speed (full flashbence data is attached) and how many writes were made over those 1500 hours to the SD card as a whole? (... not just the swap partition, since endurance of the card relates to total writes to the card). Sorry no data on this, but the card is also holding an OS. Ubuntu 8.10 till recently and XOpup the last couple of weeks. Probably 1000 of the 1500 hours where run with this alternative OS, so I would think a lot of writes. Two caveats though, the card spend half of its life with an ext2 file system and the other half with an ext3. My Ubuntu OS was configured with `vm.swappiness=0' (no swappiness settings for the OLPC builds in the NAND). Transcend 4GB class6 Size: 3905536 /sys/devices/pci:00/:00:0c.0/mmc_host/mmc2/mmc2:8c10/name SU04G /sys/block/mmcblk0/device/ name SDC oemid 0x5356, manfid 0x1c, hwrev 0x1, fwrev 0x0, serial 0x05593bca, scr 0235, csd 400e00325f591dcb7f800a40 bash-4.1# ./flashbench -a /dev/mmcblk0 --blocksize=1024 align 1073741824pre 604µs on 669µs post 576µs diff 79.1µs align 536870912 pre 586µs on 658µs post 568µs diff 81.3µs align 268435456 pre 579µs on 658µs post 567µs diff 85.1µs align 134217728 pre 585µs on 655µs post 563µs diff 81.3µs align 67108864 pre 582µs on 661µs post 554µs diff 92.6µs align 33554432 pre 582µs on 653µs post 563µs diff 80.6µs align 16777216 pre 587µs on 660µs post 562µs diff 85.5µs align 8388608 pre 584µs on 669µs post 566µs diff 93.7µs align 4194304 pre 589µs on 664µs post 567µs diff 86.6µs align 2097152 pre 585µs on 659µs post 569µs diff 81.3µs align 1048576 pre 588µs on 643µs post 594µs diff 52.2µs align 524288pre 588µs on 640µs post 584µs diff 54.3µs align 262144pre 580µs on 638µs post 587µs diff 54.4µs align 131072pre 584µs on 635µs post 586µs diff 49.9µs align 65536 pre 594µs on 635µs post 588µs diff 43.8µs align 32768 pre 571µs on 614µs post 563µs diff 46.9µs align 16384 pre 574µs on 609µs post 565µs diff 39.6µs align 8192 pre 572µs on 614µs post 562µs diff 46.9µs align 4096 pre 573µs on 610µs post 565µs diff 41.3µs align 2048 pre 560µs on 564µs post 558µs diff 5.55µs bash-4.1# ./flashbench -O --erasesize=$[2 * 1024 * 1024] --blocksize=$[16 * 1024] /dev/mmcblk0 --open-au-nr=4 2MiB9.38M/s 1MiB8.67M/s 512KiB 8.88M/s 256KiB 8.49M/s 128KiB 8.63M/s 64KiB 9.83M/s 32KiB 10.6M/s 16KiB 8.59M/s bash-4.1# ./flashbench -O --erasesize=$[2 * 1024 * 1024] --blocksize=$[16 * 1024] /dev/mmcblk0 --open-au-nr=5 2MiB9.96M/s 1MiB9.28M/s 512KiB 9.5M/s 256KiB 9.06M/s 128KiB 9.22M/s 64KiB 10.2M/s 32KiB 10.5M/s 16KiB 8.7M/s bash-4.1# ./flashbench -O --erasesize=$[2 * 1024 * 1024] --blocksize=$[16 * 1024] /dev/mmcblk0 --open-au-nr=6 2MiB6.65M/s 1MiB5.93M/s 512KiB 2.45M/s 256KiB 1.35M/s 128KiB 720K/s 64KiB 381K/s 32KiB 194K/s 16KiB 97.6K/s bash-4.1# ./flashbench -O --erasesize=$[2 * 1024 * 1024] --blocksize=$[16 * 1024] /dev/mmcblk0 --random --open-au-nr=4 2MiB5.96M/s 1MiB5.55M/s 512KiB 5.1M/s 256KiB 4.91M/s 128KiB 4.8M/s 64KiB 4.75M/s 32KiB 4.09M/s 16KiB 3.3M/s bash-4.1# ./flashbench -O --erasesize=$[2 * 1024 * 1024] --blocksize=$[16 * 1024] /dev/mmcblk0 --random --open-au-nr=5 2MiB6.05M/s 1MiB5.61M/s 512KiB 5.12M/s 256KiB 4.91M/s 128KiB 4.8M/s 64KiB 4.7M/s 32KiB 4.11M/s 16KiB 3.28M/s bash-4.1# ./flashbench -O --erasesize=$[2 * 1024 * 1024] --blocksize=$[4 * 1024] /dev/mmcblk0 --random --open-au-nr=6 2MiB7.97M/s 1MiB4.28M/s 512KiB 2.52M/s 256KiB 1.36M/s 128KiB 722K/s 64KiB 378K/s 32KiB 193K/s 16KiB 97.5K/s bash-4.1# ./flashbench --erasesize=$[2 * 1024 * 1024] --findfat --random /dev/mmcblk0 2MiB5M/s 7.62M/s 7.14M/s 12.6M/s 12.5M/s 12.3M/s 1MiB4.78M/s 4.85M/s 4.82M/s 3.46M/s 3.47M/s 3.52M/s 512KiB 3.52M/s 3.54M/s 3.53M/s 3.53M/s 3.53M/s
Re: XO-1.75 RAM
On Thu, Apr 14, 2011 at 01:21:23AM -0700, Yioryos Asprobounitis wrote: That was/is a $15 Transcend 4GB class 6 card that not only can have 5 erase blocks open but also has an impressive random w/r speed (full flashbence data is attached) Okay, thanks. I don't know a deployment willing to fork out an extra $15 per laptop for performance ... but others in my team might know. Sounds like a very nice card if one can afford it, and if the current batch persists in the same endurance and performance. -- James Cameron http://quozl.linux.org.au/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: XO-1.75 RAM
Might 1GB of RAM become a performance bottleneck? I myself am skeptical of efforts to use the OLPC where a desktop system might be more effective. I've run various large applications on an XO-1.5 system, and have not myself experienced memory shortage. Unless the RAM chips on the XO-1.75 are socketed (and thus easily replaceable), it seems to me that it would be easier to add swap space (rather than RAM) to those systems used to run particularly memory-hungry applications (such as video editing). mikus ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: XO-1.75 RAM
On 14 April 2011 06:16, Mikus Grinbergs mi...@bga.com wrote: Might 1GB of RAM become a performance bottleneck? I myself am skeptical of efforts to use the OLPC where a desktop system might be more effective. I've run various large applications on an XO-1.5 system, and have not myself experienced memory shortage. Unless the RAM chips on the XO-1.75 are socketed (and thus easily replaceable), it seems to me that it would be easier to add swap space (rather than RAM) to those systems used to run particularly memory-hungry applications (such as video editing). Flash storage is mush slower than spinning hard drives and wears out far more quickly. I don't think using flash for swap is a good idea. More RAM can be used for write caching, which can greatly improve performance (depending on the load). Sridhar ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: XO-1.75 RAM
On 14 April 2011 06:16, Mikus Grinbergs mi...@bga.com wrote: Unless the RAM chips on the XO-1.75 are socketed (and thus easily replaceable), This seems unlikely. Socketing adds cost up front, and low cost is a primary goal. Also the demand for upgrade would be relatively low. ... particularly memory-hungry applications (such as video editing). Video editing requires low latency storage rather than large amounts of memory. The files, being often larger than memory, cause the cache to be filled with single-use data, which is a waste. You get the same cache effect just by copying the files. -- James Cameron http://quozl.linux.org.au/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
