Tracing Merge System 'Integrated Trace' - Linux Foundation Events

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When was write_tsc executed?• TSC offset events output timestamp(TSC value) andprevious TSC offset.• When TSC offset is changed, guest does not operateon the VCPU.– A merge tool can apply previous TSC offset or next TSCoffset for each trace event of a guest.Tg = TSC_host + prev_offsetkvm_exitwrite_tsc_offsetkvm_entryExecute write_tscIs this a general method?Event AEvent BEvent CCopyright (c) 2013 Hitachi LTD., Yokohama Research Laboratory. All right reservedTgPrevious offsetNext offset30
General or not (1)• To search the point where the guest executedtsc_write, we find ‘n’ which satisfies the conditionTg = TSC_host + prev_offsetTn < Tg < Tn+1 or Tn+1 < Tn < Tgmonotonic proccedgo backward• If write_tsc is executed only once on a guest, themethod is useful.timestampeventsPrevious offset(=boot)timestampeventsTnTn+180 A event(guest)110 B event(guest)500 C event(guest)505 D event(guest)TgTnTn+180 A event(guest)110 B event(guest)35 C event(guest)40 D event(guest)Next offsetCopyright (c) 2013 Hitachi LTD., Yokohama Research Laboratory. All right reserved31
Page 1 and 2: Tracing Merge System ‘Integrated
Page 3 and 4: Agenda1. What is “Integrated trac
Page 5 and 6: Why do we need to merge tracing?•
Page 7 and 8: Our goal imageguest1trace dataof gu
Page 9 and 10: Merge tracing data• Merge tracing
Page 11 and 12: Read TSC value on a guest• TSC va
Page 13 and 14: Getting TSC offset• When a kernel
Page 15: How do we output a TSC offset?1. Ad
Page 18 and 19: TSC offset tracepoint• TSC offset
Page 20 and 21: Merging procedure1. Check if the kv
Page 22 and 23: Basic merging procedure• tsc_offs
Page 24 and 25: Basic merging procedure• tsc_offs
Page 26 and 27: Merging procedure1. Check if the kv
Page 28 and 29: Execute write_tsc on a guest(2)•
Page 32 and 33: General or not (2)• If all timest
Page 34 and 35: Agenda1. What is “Integrated trac
Page 36 and 37: 1. Using cyclictest• We use cycli
Page 38 and 39: 3. Apply the integrated trace• Ho
Page 40 and 41: 5. Check trace data~3.7ms!!TSC=7800
Page 42: Patch Setpatch set of outputting ts

Tracing Merge System 'Integrated Trace' - Linux Foundation Events

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