Firefox/Goals/2010Q1/IO Reduction

Pitch

Reducing I/O operations on the main thread will remove potential points of hanging that users experience, providing a substantially better user experience to our users. Removing at least 50% of our current I/O operations (as of January 1, 2010) from the main thread.

Goals

• Reduce at least 50% of the I/O operations on the main thread (read, write, fsync, fstat) based on a certain set of criteria.

Non-Goals

• Reduce the number of I/O operations that we do

Status

• IN FLIGHT
• Project Lead: sdwilsh
• Project Members: Bjarne, mak, rflint, Unfocused
• Cookie stuff should have a new patch up this week. About 27% of the IO has been removed from mozilla-central. See this table for more details

Timeline / Milestones

Initial numbers from v1.1 of the criteria are:

• write counts: 4084
• read counts: 1073
• fsync counts: 49
• total count: 5206

These are the bugs of interest:

Bug	Owner	Status	reads	writes	fsyncs	fstats	% I/O Responsible
bug 513074 - remove sync writes from current cache	Bjarne	landed		1423	3		27.3%
bug 536978 - Cookies should write asynchronously	sdwilsh	need to address review comments		1137			21.8%
bug 540765	mak	some bits landed in bug bug 522855. Revising Favicon Service interface to make it async.	10	111			2.3%
bug 513008 - Eliminate synchronous reads from cache	michal.novotny	wip patch up; discussion ongoing	75				1.4%
bug 546255 - Make nsIBrowserHistory.[un]registerOpenPage async	Unfocused		?	?			?
bug 541779 - Make site-specific zoom check asynchronous	rflint	waiting on review	?	?			?
bug 461199 - Make visitedness checks asynchronous	sdwilsh	landed	?	?			?

Delivery Requirements

This work must be landed on mozilla-central by March 31, 2010.

Constraints

None

Dependencies

None

Testing

Our normal automated testing should be sufficient here. Numbers of calls are generated by this DTrace script.

Related Projects

None