Re: [tip:perf/core] perf: Add group scheduling transactional APIs

From: Paul Mackerras
Date: Mon May 10 2010 - 07:39:14 EST


On Mon, May 10, 2010 at 10:11:55AM +0200, Peter Zijlstra wrote:

> Can't you compute n_txn_start by subtracting n_added from n_events ?

Well, n_added says how many have been added since hw_perf_disable, and
we could get multiple transactions inside a hw_perf_disable/enable
pair, if we're scheduling multiple groups on. So n_events - n_added
doesn't tell us how many have been added in this transaction -- unless
I'm mistaken and there is a one transaction per hw_perf_disable/enable
rule, but I didn't see that written anywhere, and it does seem to be
explicitly one transaction per group.

Paul.
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