RFR: 8201318: Introduce GCThreadLocalData to abstract GC-specific data belonging to a thread (original) (raw)

Robbin Ehn robbin.ehn at oracle.com
Tue Apr 10 15:59:06 UTC 2018

On 2018-04-10 17:47, Aleksey Shipilev wrote:

On 04/10/2018 05:25 PM, Robbin Ehn wrote:

Had quick look, what I saw looked good. (not a full review) Is there a reason for moving the gc data to 'zero offset' in Thread? Oh! I missed that, and I fully agree with this move. At least one reason I see, smaller offsets against TLS open up opportunities for denser code-generation when e.g. GC barriers poll thread-local data. Right now SATB barrier generates something like "cmpb $0x0, 0x3d8(%r15)", while it could generate just "cmpb $0x0, 0x0(%r15)" now :)

Yes, but it pushes down e.g.: 333 volatile void* _polling_page; // Thread local polling page Which may not matter, as long as it's on the first page I suppose.

/Robbin

Thanks, -Aleksey

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