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<div>Hi Raj,</div><div>You've sent a total of 9 messages so far. Please, STOP spamming the list.</div><div><a href="http://lists.r-forge.r-project.org/pipermail/datatable-help/2013-July/thread.html" style="color: rgb(0, 106, 227); ">http://lists.r-forge.r-project.org/pipermail/datatable-help/2013-July/thread.html</a></div>
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<div><div><br></div><div>Arun</div><div><br></div></div>
<p style="color: #A0A0A8;">On Saturday, July 13, 2013 at 2:04 AM, Raj Dasgupta wrote:</p>
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<span><div><div><div style="color:#000; background-color:#fff; font-family:bookman old style, new york, times, serif;font-size:10pt"><div style="font-size: 10pt;"><br>Hi all,</div><div style="font-size: 10pt;"><br></div><div style="font-size: 10pt;">I have been looking at lowering the time spent in I/O while using fread on a csv file. Following a suggestion on the mailing list, I attempted to use fread on a csv file stored on a ramdisk. It took 5 times longer to read from the Ram Disk than it did to read from the SSD.</div><div style="font-size: 10pt;"><br></div><div style="font-size: 10pt;">I presume this has to do with the fact that the data is being copied from RAM to RAM and requires more effort rather than from Disk to RAM.</div><div style="font-size: 10pt;"><br></div><div style="font-size: 10pt;">Any suggestions on if there are alternative methods to read files in faster using a RAM Disk would be very
helpful.</div><div style="font-size: 10pt;"><br></div><div style="font-size: 10pt;">Benchmarks on time taken for reading from SSD vs Ramdisk on the same 416MB file is given below</div><div style="font-size: 10pt;"><br></div><div style="font-size: 10pt;">####</div><div style="font-size: 10pt;"><br></div><div style="color: rgb(0, 0, 0); font-family: 'bookman old style', 'new york', times, serif; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div><font size="2">> timer = proc.time(); z <- fread("testInRAM.csv"); proc.time() - timer</font></div><div><font size="2"> user system elapsed </font></div><div><font size="2"> 25.067 0.433
25.485 ##### Read from RAMDisk</font></div><div><font size="2"><br></font></div><div><font size="2">> setwd("/Users/xbsd/")</font></div><div><font size="2">> timer = proc.time(); z <- fread("test.csv"); proc.time() - timer</font></div><div><font size="2"> user system elapsed </font></div><div><font size="2"> 5.507 0.177 5.680 ###### Read from SSD</font></div><div><font size="2"><br></font></div><div><font size="2">> system("ls -alh test.csv")</font></div><div><font size="2">-rw-r--r-- 1 xbsd staff 416M Jul 12 19:30 test.csv</font></div><div><font size="2"><br></font></div><div><font size="2">> system("ls -alh /Volumes/ramdisk/testInRAM.csv")</font></div><div><font size="2">-rw-r--r-- 1 xbsd staff 416M Jul 12 19:32 /Volumes/ramdisk/testInRAM.csv</font></div><div><font size="2"><br></font></div><div><font size="2">Thanks in
advance,</font></div><div><font size="2"><br></font></div><div><font size="2">- Raj.</font></div><div><font size="2"><br></font></div></div></div></div><div><div>_______________________________________________</div><div>datatable-help mailing list</div><div><a href="mailto:datatable-help@lists.r-forge.r-project.org">datatable-help@lists.r-forge.r-project.org</a></div><div><a href="https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help">https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help</a></div></div></div></span>
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