[parsec-users] About VIPS's synchronization
jzz at mit.edu
Thu Mar 7 06:56:05 EST 2013
Thanks a lot!
Sent from my iPhone
On Mar 7, 2013, at 4:10 AM, jcupitt at gmail.com wrote:
> Hi Justin,
> On 7 March 2013 05:20, Zhunping Zhang <jzz at mit.edu> wrote:
>> Wonder if anyone can enlighten me how VIPS handles input synchronization. As I
>> understand, an operation in VIPS read inputs from several images and outputs to
>> one. The output images is shredded into blocks to be processed in parallel.
>> Evaluating two different blocks might depend on the same pixel in the input
>> images, and some synchronization method is needed to avoid races. May I know
>> how VIPs implement this? (Pointing to line numbers would be really helpful.)
> I wrote a post about this:
> The PARSEC benchmark uses direct access (the first method described in that post).
> I don't know which version of vips is bundled in current PARSEC, but looking at libvips git master, the methods you need are vips_region_image(), which selects a rectangular area of a memory-mapped file:
> Which in turn calls vips_window_ref() to get a reference to a chunk of a file:
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