Massively-improved memory use of Firefox 3

Posted by Rakesh in Technology      1 comment

Jan
31

It’s great to see the massively-improved memory use of Firefox 3. It far excels anything that we offered, previously, and seems to best all other browsers on the platform.

Now, obviously, Windows Vista isn’t the only platform available. I, personally, use Debian (Linux) and am interested to see the memory numbers there as well.

The short summary is Windows Vista (Commit Size) and Linux (RSS) provide pretty accurate memory measurement numbers while Windows XP and Mac OS X do not.

On Mac, If you look at Activity Monitor it will look like we’re using more memory than we actually are. Mac OS X has a similar, but different, problem to Windows XP. After extensive testing and confirmation from Apple employees we realized that there was no way for an allocator to give unused pages of memory back while keeping the address range reserved.. (You can unmap them and remap them, but that causes some race conditions and isn’t as performant.) There are APIs that claim to do it (both madvise() and msync()) but they don’t actually do anything. It does appear that pages mapped in that haven’t been written to won’t be accounted for in memory stats, but you’ve written to them they’re going to show as taking up space until you unmap them. Since allocators will reuse space, you generally won’t have that many pages mapped in that haven’t been written to. Our application can and will reuse the free pages, so you should see Firefox hit a peak number and generally not grow a lot higher than that.

I think it’s great to see these numbers come in. In many ways Firefox 3 is going to be a very different browser from its previous instantiations. I’ve, personally, been using it as my primary browser for a while now and have enjoyed the increased performance. It really does feel – and really even look – like a whole new browser.

Click here for the real story

It’s great to see the massively-improved memory use of Firefox 3. It far excels anything that we offered, previously, and seems to best all other browsers on the platform.

Now, obviously, Windows Vista isn’t the only platform available. I, personally, use Debian (Linux) and am interested to see the memory numbers there as well.

The short summary is Windows Vista (Commit Size) and Linux (RSS) provide pretty accurate memory measurement numbers while Windows XP and Mac OS X do not.

On Mac, If you look at Activity Monitor it will look like we’re using more memory than we actually are. Mac OS X has a similar, but different, problem to Windows XP. After extensive testing and confirmation from Apple employees we realized that there was no way for an allocator to give unused pages of memory back while keeping the address range reserved.. (You can unmap them and remap them, but that causes some race conditions and isn’t as performant.) There are APIs that claim to do it (both madvise() and msync()) but they don’t actually do anything. It does appear that pages mapped in that haven’t been written to won’t be accounted for in memory stats, but you’ve written to them they’re going to show as taking up space until you unmap them. Since allocators will reuse space, you generally won’t have that many pages mapped in that haven’t been written to. Our application can and will reuse the free pages, so you should see Firefox hit a peak number and generally not grow a lot higher than that.

I think it’s great to see these numbers come in. In many ways Firefox 3 is going to be a very different browser from its previous instantiations. I’ve, personally, been using it as my primary browser for a while now and have enjoyed the increased performance. It really does feel – and really even look – like a whole new browser.

Click here for the real story

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1. Ten Easy and Quick Firefox 3.6 Installation Tips