Hi Raj,
You've sent a total of 9 messages so far. Please, STOP spamming the list.
http://lists.r-forge.r-project.org/pipermail/datatable-help/2013-July/thread.html
Arun
On Saturday, July 13, 2013 at 2:04 AM, Raj Dasgupta wrote:
>
> Hi all,
>
> 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.
>
> 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.
>
> Any suggestions on if there are alternative methods to read files in faster
> using a RAM Disk would be very helpful.
>
> Benchmarks on time taken for reading from SSD vs Ramdisk on the same 416MB
> file is given below
>
> ####
>
> > timer = proc.time(); z <- fread("testInRAM.csv"); proc.time() - timer
> user system elapsed
> 25.067 0.433 25.485 ##### Read from RAMDisk
>
> > setwd("/Users/xbsd/")
> > timer = proc.time(); z <- fread("test.csv"); proc.time() - timer
> user system elapsed
> 5.507 0.177 5.680 ###### Read from SSD
>
> > system("ls -alh test.csv")
> -rw-r--r-- 1 xbsd staff 416M Jul 12 19:30 test.csv
>
> > system("ls -alh /Volumes/ramdisk/testInRAM.csv")
> -rw-r--r-- 1 xbsd staff 416M Jul 12 19:32 /Volumes/ramdisk/testInRAM.csv
>
> Thanks in advance,
>
> - Raj.
>
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