Messages in this thread |  | | | Subject | Re: [PATCH 08/11] perf tool: precise mode requires exclude_guest | | From | Peter Zijlstra <> | | Date | Thu, 26 Jul 2012 10:08:29 +0200 |
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On Wed, 2012-07-25 at 23:16 -0600, David Ahern wrote:
> Peter's patch (see https://lkml.org/lkml/2012/7/9/298) changes kernel > side to require the use of exclude_guest if the precise modifier is > used, returning -EOPNOTSUPP if exclude_guest is not set. This patch goes > after the user experience: Today if a user specifies -e <event>:p all > other modifiers are reset - including exclude_guest. Going forward we > need :p to imply :pH if a user has not specified a GH modifer. > > We could do nothing and handle the unsupported error and try setting the > exclude_guest option - like perf handles other new parameters. But > EOPNOTSUPP is not uniquely tied to this error -- e.g., it could be the > BTS is not supported (:pp). Also, we have no easy way to discriminate :p > from :pG or :pGH. It seems to me perf should not silently undo a user > request on the modifier, but inform the user the request is wrong. For > example if a user request -e cycles:pG it should not be silently turned > into :pH. > > And then yesterday, Robert stated that none of the exclude_xxxx > modifiers can be set for the AMD if the precise modifier is used, so we > cannot blindly set exclude_guest if precise_ip is set. > > So, seems to me perf need's one action for Intel processors and another > for AMD.
No, we just need to teach the IBS code about SVM enter/exit.
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