Date: Wed, 31 Aug 2016 08:02:06 -0500 From: Karl Denninger <karl@denninger.net> To: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Kernel UMA current occupancy statistics Message-ID: <18fdca3b-9002-db60-504b-388c628fab0e@denninger.net>
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This is a cryptographically signed message in MIME format. --------------ms020100000504020001050204 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Working on the ZFS ARC code I'm trying to find documentation on the means by which I can determine the occupancy of a UMA slab. There is a userland set of calls but I assume those are not the correct way to approach this in the kernel context. include/sys/vm/uma.h declares that the returned structure is to be opaque to users of the facility, and the only occupancy-related function I can find is uma_zone_get_cur, which gives me the number of items allocated but uma_zone_get_max states that it will return "0" if no limit on allocations has been set. Any hints on how to determine, if for example there are 50,000 "units" of memory that are currently held out of kmem in a given slab how many are actually allocated and how many are free and reusable without a further kernel memory allocation? What I'm trying to determine is this (from vmstat -z): ITEM SIZE LIMIT USED FREE REQ FAIL SLEEP zio_buf_512: 512, 0, 79865, 199359, 6495950, 0, 0 In other words how do I programmatically, inside a kernel routine (in this case zfs/arc.c) retrieve the "used" and "free" values if I have a given slab's pointer (which I can use to call kmem_cache_reap_now)? Thanks in advance; --=20 Karl Denninger karl@denninger.net <mailto:karl@denninger.net> /The Market Ticker/ /[S/MIME encrypted email preferred]/ --------------ms020100000504020001050204 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgMFADCABgkqhkiG9w0BBwEAAKCC Bl8wggZbMIIEQ6ADAgECAgEpMA0GCSqGSIb3DQEBCwUAMIGQMQswCQYDVQQGEwJVUzEQMA4G A1UECBMHRmxvcmlkYTESMBAGA1UEBxMJTmljZXZpbGxlMRkwFwYDVQQKExBDdWRhIFN5c3Rl bXMgTExDMRwwGgYDVQQDExNDdWRhIFN5c3RlbXMgTExDIENBMSIwIAYJKoZIhvcNAQkBFhND dWRhIFN5c3RlbXMgTExDIENBMB4XDTE1MDQyMTAyMjE1OVoXDTIwMDQxOTAyMjE1OVowWjEL MAkGA1UEBhMCVVMxEDAOBgNVBAgTB0Zsb3JpZGExGTAXBgNVBAoTEEN1ZGEgU3lzdGVtcyBM TEMxHjAcBgNVBAMTFUthcmwgRGVubmluZ2VyIChPQ1NQKTCCAiIwDQYJKoZIhvcNAQEBBQAD ggIPADCCAgoCggIBALmEWPhAdphrWd4K5VTvE5pxL3blRQPyGF3ApjUjgtavqU1Y8pbI3Byg XDj2/Uz9Si8XVj/kNbKEjkRh5SsNvx3Fc0oQ1uVjyCq7zC/kctF7yLzQbvWnU4grAPZ3IuAp 3/fFxIVaXpxEdKmyZAVDhk9az+IgHH43rdJRIMzxJ5vqQMb+n2EjadVqiGPbtG9aZEImlq7f IYDTnKyToi23PAnkPwwT+q1IkI2DTvf2jzWrhLR5DTX0fUYC0nxlHWbjgpiapyJWtR7K2YQO aevQb/3vN9gSojT2h+cBem7QIj6U69rEYcEDvPyCMXEV9VcXdcmW42LSRsPvZcBHFkWAJqMZ Myiz4kumaP+s+cIDaXitR/szoqDKGSHM4CPAZV9Yh8asvxQL5uDxz5wvLPgS5yS8K/o7zDR5 vNkMCyfYQuR6PAJxVOk5Arqvj9lfP3JSVapwbr01CoWDBkpuJlKfpQIEeC/pcCBKknllbMYq yHBO2TipLyO5Ocd1nhN/nOsO+C+j31lQHfOMRZaPQykXVPWG5BbhWT7ttX4vy5hOW6yJgeT/ o3apynlp1cEavkQRS8uJHoQszF6KIrQMID/JfySWvVQ4ksnfzwB2lRomrdrwnQ4eG/HBS+0l eozwOJNDIBlAP+hLe8A5oWZgooIIK/SulUAsfI6Sgd8dTZTTYmlhAgMBAAGjgfQwgfEwNwYI KwYBBQUHAQEEKzApMCcGCCsGAQUFBzABhhtodHRwOi8vY3VkYXN5c3RlbXMubmV0Ojg4ODgw CQYDVR0TBAIwADARBglghkgBhvhCAQEEBAMCBaAwCwYDVR0PBAQDAgXgMCwGCWCGSAGG+EIB DQQfFh1PcGVuU1NMIEdlbmVyYXRlZCBDZXJ0aWZpY2F0ZTAdBgNVHQ4EFgQUxRyULenJaFwX RtT79aNmIB/u5VkwHwYDVR0jBBgwFoAUJHGbnYV9/N3dvbDKkpQDofrTbTUwHQYDVR0RBBYw FIESa2FybEBkZW5uaW5nZXIubmV0MA0GCSqGSIb3DQEBCwUAA4ICAQBPf3cYtmKowmGIYsm6 eBinJu7QVWvxi1vqnBz3KE+HapqoIZS8/PolB/hwiY0UAE1RsjBJ7yEjihVRwummSBvkoOyf G30uPn4yg4vbJkR9lTz8d21fPshWETa6DBh2jx2Qf13LZpr3Pj2fTtlu6xMYKzg7cSDgd2bO sJGH/rcvva9Spkx5Vfq0RyOrYph9boshRN3D4tbWgBAcX9POdXCVfJONDxhfBuPHsJ6vEmPb An+XL5Yl26XYFPiODQ+Qbk44Ot1kt9s7oS3dVUrh92Qv0G3J3DF+Vt6C15nED+f+bk4gScu+ JHT7RjEmfa18GT8DcT//D1zEke1Ymhb41JH+GyZchDRWtjxsS5OBFMzrju7d264zJUFtX7iJ 3xvpKN7VcZKNtB6dLShj3v/XDsQVQWXmR/1YKWZ93C3LpRs2Y5nYdn6gEOpL/WfQFThtfnat HNc7fNs5vjotaYpBl5H8+VCautKbGOs219uQbhGZLYTv6okuKcY8W+4EJEtK0xB08vqr9Jd0 FS9MGjQE++GWo+5eQxFt6nUENHbVYnsr6bYPQsZH0CRNycgTG9MwY/UIXOf4W034UpR82TBG 1LiMsYfb8ahQJhs3wdf1nzipIjRwoZKT1vGXh/cj3gwSr64GfenURBxaFZA5O1acOZUjPrRT n3ci4McYW/0WVVA3lDGCBRMwggUPAgEBMIGWMIGQMQswCQYDVQQGEwJVUzEQMA4GA1UECBMH RmxvcmlkYTESMBAGA1UEBxMJTmljZXZpbGxlMRkwFwYDVQQKExBDdWRhIFN5c3RlbXMgTExD MRwwGgYDVQQDExNDdWRhIFN5c3RlbXMgTExDIENBMSIwIAYJKoZIhvcNAQkBFhNDdWRhIFN5 c3RlbXMgTExDIENBAgEpMA0GCWCGSAFlAwQCAwUAoIICTTAYBgkqhkiG9w0BCQMxCwYJKoZI hvcNAQcBMBwGCSqGSIb3DQEJBTEPFw0xNjA4MzExMzAyMDZaME8GCSqGSIb3DQEJBDFCBEAT 1lW3fJnaK7IA1Wgb5BiisO4yZYtMKzBGIWAzA8wBA/0Vh6WPPwn9FudtZTGFNOqzS8ylIkth neE0qtFXkp2fMGwGCSqGSIb3DQEJDzFfMF0wCwYJYIZIAWUDBAEqMAsGCWCGSAFlAwQBAjAK BggqhkiG9w0DBzAOBggqhkiG9w0DAgICAIAwDQYIKoZIhvcNAwICAUAwBwYFKw4DAgcwDQYI KoZIhvcNAwICASgwgacGCSsGAQQBgjcQBDGBmTCBljCBkDELMAkGA1UEBhMCVVMxEDAOBgNV BAgTB0Zsb3JpZGExEjAQBgNVBAcTCU5pY2V2aWxsZTEZMBcGA1UEChMQQ3VkYSBTeXN0ZW1z IExMQzEcMBoGA1UEAxMTQ3VkYSBTeXN0ZW1zIExMQyBDQTEiMCAGCSqGSIb3DQEJARYTQ3Vk YSBTeXN0ZW1zIExMQyBDQQIBKTCBqQYLKoZIhvcNAQkQAgsxgZmggZYwgZAxCzAJBgNVBAYT AlVTMRAwDgYDVQQIEwdGbG9yaWRhMRIwEAYDVQQHEwlOaWNldmlsbGUxGTAXBgNVBAoTEEN1 ZGEgU3lzdGVtcyBMTEMxHDAaBgNVBAMTE0N1ZGEgU3lzdGVtcyBMTEMgQ0ExIjAgBgkqhkiG 9w0BCQEWE0N1ZGEgU3lzdGVtcyBMTEMgQ0ECASkwDQYJKoZIhvcNAQEBBQAEggIAM/1gwcy2 y3+/TrArpILrssnHiWcko3v/kwQLE6do//uQrh0Ym0HbZWcRDGuQtg4Kxx+Aqb6yd82X5St4 lfE/Z0oC7Dl9vJE6RWZfkVli0C6WPTBQEYmyqnhzWvek6LkH/y0slC+eYBfzbr+eC+uOVYB+ guM9TrbhJbdwAc2uCpsJo+ommekUWKWcobufqzKfPGfFJCmekFBmfstnH3Nc/pB2FzZ+2Eyz ozVW37J5Rt3tIyfBWC+EDjmNPp0C8qR2iN2KA+XaiYc1whSn5R8159sSfIgK40oL7hrMp+Eg /hEcgHzBGGBmPQwPwI0MxEmTL9qrX5IHnVEnazf1Recv6wbad2Ux24CXHEj6Tb92mTLdhSfz fGldnh8QSjEL/wrFEhE2hk+u6yn36Ic548qifCTUGOL6NxECCCUzhweq2s6kfC3J8bPh9p+7 bS3FBEXVRM1GjtGEgZPwh/QQPOMEU7nQDW3MsS+CCXGaAkbwZcMOa/iLZqkJri7RNlIWJDnj I1/GXPxnvojTuGC+7UoIqRk00r1ue4ADoQgNf17lKGt/zGVij2iHMFgUl/NZ3U8JQr2QQq2l YLQuWeFZ2NkgrIxOef24F8RNAYt+bjTfyw3PFtOG7f1kTQCSWFkTXGpar+U3t6TvQqh1zJy+ Cf9Sq4js4YUx3HmhoJpbXhWPKiQAAAAAAAA= --------------ms020100000504020001050204--
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