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This collection of QOS domains is >>>> +referred to as GMBA control domain. The GMBA control domain is created by >>>> +setting the same GMBA limits in one or more QoS domains. Setting the default >>>> +max_bandwidth excludes the QoS domain from being part of GMBA control domain. >>> I don't see any checks that the user sets the *SAME* GMBA limits. >>> >>> What happens if the user ignores the dosumentation and sets different >>> limits? >> Good point. Adding checks could be challenging when users update each schema individually with different values. We don't know which one value is the one he is intending to keep. >> >>> ... snip ... >>> >>> +  # cat schemata >>> +    GMB:0=2048;1=2048;2=2048;3=2048 >>> +     MB:0=4096;1=4096;2=4096;3=4096 >>> +     L3:0=ffff;1=ffff;2=ffff;3=ffff >>> + >>> +  # echo "GMB:0=8;2=8" > schemata >>> +  # cat schemata >>> +    GMB:0=   8;1=2048;2=   8;3=2048 >>> +     MB:0=4096;1=4096;2=4096;3=4096 >>> +     L3:0=ffff;1=ffff;2=ffff;3=ffff >>> >>> Can the user go on to set: >>> >>>     # echo "GMB:1=10;3=10" > schemata >>> >>> and have domains 0 & 2 with a combined 8GB limit, >>> while domains 1 & 3 run with a combined 10GB limit? >>> Or is there a single "GMBA domain"? >> In that case, it  is still treated as a single GMBA domain, but the behavior becomes unpredictable. The hardware expert mentioned that it will default to the lowest value among all inputs in this case, 8GB. >> >> >>> Will using "2048" as the "this domain isn't limited >>> by GMBA" value come back to haunt you when some >>> system has much more than 2TB bandwidth to divide up? >> It is actually 4096 (4TB). I made a mistake in the example.  I am assuming it may not an issue in the current generation. >> >> It is expected to go up in next generation. >> >> GMB:0=4096;1=4096;2=4096;3=4096; >>    MB:0=8192;1=8192;2=8192;3=8192; >>     L3:0=ffff;1=ffff;2=ffff;3=ffff >> >> >>> Should resctrl have a non-numeric "unlimited" value >>> in the schemata file for this? >> The value 4096 corresponds to 12th bit set.  It is called U-bit. If the U bit is set then that domain is not part of the GMBA domain. >> >> I was thinking of displaying the "U" in those cases.  It may be good idea to do something like this. >> >> GMB:0=      8;1=      U;2=     8 ;3=      U; >>    MB:0=8192;1=8192;2=8192;3=8192; >>     L3:0=ffff;1=ffff;2=ffff;3=ffff >> >> >>> The "mba_MBps" feature used U32_MAX as the unlimited >>> value. But it looks somewhat ugly in the schemata >>> file: >> Yes, I agree. Non-numeric would have been better. > How would such a value be described in a generic way as part of the new schema > description format? I dont think we need any special handling.  We should report the actual numeric value for max in new format. > Since the proposed format contains a maximum I think just using that > value may be simplest while matching what is currently displayed for > "unlimited" MB, no? > Yea.  I t should be ok to display the max value here. Thanks Babu