From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: [RFC] Credit1: Make weight per-vcpu Date: Thu, 12 Aug 2010 17:29:55 +0100 Message-ID: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary=0015175cdc26633c63048da2e0ee Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org --0015175cdc26633c63048da2e0ee Content-Type: text/plain; charset=ISO-8859-1 At the moment, the "weight" parameter for a VM is set on a per-VM basis. This means that when cpu time is scarce, two VMs with the same weight will be given the same amount of total cpu time, no matter how many vcpus it has. I.e., if a VM has 1 vcpu, that vcpu will get x% of cpu time; if a VM has 2 vcpus, each vcpu will get (x/2)% of the cpu time. I believe this is a counter-intuitive interface. Users often choose to add vcpus; when they do so, it's with the expectation that a VM will need and use more cpu time. In my experience, however, users rarely change the weight parameter. So the normal course of events is for a user to decide a VM needs more processing power, add more cpus, but doesn't change the weight. The VM still gets the same amount of cpu time, but less efficiently allocated (because it's divided). The attached patch changes the meaning of the "weight" parameter, to be per-vcpu. Each vcpu is given the weight. So if you add an extra vcpu, your VM will get more cpu time as well. This patch has been in Citrix XenServer for several releases now (checked in June 2008), and seems to fit more with customer expectations. -George --0015175cdc26633c63048da2e0ee Content-Type: application/octet-stream; name="scheduler.per-vcpu-weight" Content-Disposition: attachment; filename="scheduler.per-vcpu-weight" Content-Transfer-Encoding: base64 X-Attachment-Id: f_gcrtqgb40 Q3JlZGl0MTogTWFrZSB3ZWlnaHQgcGVyLXZjcHUKCkNoYW5nZSB0aGUgbWVhbmluZyBvZiBjcmVk aXQxJ3MgIndlaWdodCIgcGFyYW1ldGVyIHRvIGJlIHBlci12Y3B1LApyYXRoZXIgdGhhbiBwZXIt Vk0uICAKClNpZ25lZC1vZmYtYnk6IEdlb3JnZSBEdW5sYXAgPGdlb3JnZS5kdW5sYXBAZXUuY2l0 cml4LmNvbT4KCmRpZmYgLXIgZjQ1MDI2ZWM4ZGI1IHhlbi9jb21tb24vc2NoZWRfY3JlZGl0LmMK LS0tIGEveGVuL2NvbW1vbi9zY2hlZF9jcmVkaXQuYwlNb24gQXVnIDA5IDE4OjI5OjUwIDIwMTAg KzAxMDAKKysrIGIveGVuL2NvbW1vbi9zY2hlZF9jcmVkaXQuYwlUdWUgQXVnIDEwIDE1OjIzOjI0 IDIwMTAgKzAxMDAKQEAgLTU1NSwxMCArNTU1LDExIEBACiAKICAgICAgICAgc2RvbS0+YWN0aXZl X3ZjcHVfY291bnQrKzsKICAgICAgICAgbGlzdF9hZGQoJnN2Yy0+YWN0aXZlX3ZjcHVfZWxlbSwg JnNkb20tPmFjdGl2ZV92Y3B1KTsKKyAgICAgICAgLyogTWFrZSB3ZWlnaHQgcGVyLXZjcHUgKi8K KyAgICAgICAgcHJ2LT53ZWlnaHQgKz0gc2RvbS0+d2VpZ2h0OwogICAgICAgICBpZiAoIGxpc3Rf ZW1wdHkoJnNkb20tPmFjdGl2ZV9zZG9tX2VsZW0pICkKICAgICAgICAgewogICAgICAgICAgICAg bGlzdF9hZGQoJnNkb20tPmFjdGl2ZV9zZG9tX2VsZW0sICZwcnYtPmFjdGl2ZV9zZG9tKTsKLSAg ICAgICAgICAgIHBydi0+d2VpZ2h0ICs9IHNkb20tPndlaWdodDsKICAgICAgICAgfQogICAgIH0K IApAQCAtNTc2LDEzICs1NzcsMTMgQEAKICAgICBDU0NIRURfVkNQVV9TVEFUX0NSQU5LKHN2Yywg c3RhdGVfaWRsZSk7CiAgICAgQ1NDSEVEX1NUQVRfQ1JBTksoYWNjdF92Y3B1X2lkbGUpOwogCisg ICAgQlVHX09OKCBwcnYtPndlaWdodCA8IHNkb20tPndlaWdodCApOwogICAgIHNkb20tPmFjdGl2 ZV92Y3B1X2NvdW50LS07CiAgICAgbGlzdF9kZWxfaW5pdCgmc3ZjLT5hY3RpdmVfdmNwdV9lbGVt KTsKKyAgICBwcnYtPndlaWdodCAtPSBzZG9tLT53ZWlnaHQ7CiAgICAgaWYgKCBsaXN0X2VtcHR5 KCZzZG9tLT5hY3RpdmVfdmNwdSkgKQogICAgIHsKLSAgICAgICAgQlVHX09OKCBwcnYtPndlaWdo dCA8IHNkb20tPndlaWdodCApOwogICAgICAgICBsaXN0X2RlbF9pbml0KCZzZG9tLT5hY3RpdmVf c2RvbV9lbGVtKTsKLSAgICAgICAgcHJ2LT53ZWlnaHQgLT0gc2RvbS0+d2VpZ2h0OwogICAgIH0K IH0KIApAQCAtODA0LDggKzgwNSw4IEBACiAgICAgICAgIHsKICAgICAgICAgICAgIGlmICggIWxp c3RfZW1wdHkoJnNkb20tPmFjdGl2ZV9zZG9tX2VsZW0pICkKICAgICAgICAgICAgIHsKLSAgICAg ICAgICAgICAgICBwcnYtPndlaWdodCAtPSBzZG9tLT53ZWlnaHQ7Ci0gICAgICAgICAgICAgICAg cHJ2LT53ZWlnaHQgKz0gb3AtPnUuY3JlZGl0LndlaWdodDsKKyAgICAgICAgICAgICAgICBwcnYt PndlaWdodCAtPSBzZG9tLT53ZWlnaHQgKiBzZG9tLT5hY3RpdmVfdmNwdV9jb3VudDsKKyAgICAg ICAgICAgICAgICBwcnYtPndlaWdodCArPSBvcC0+dS5jcmVkaXQud2VpZ2h0ICogc2RvbS0+YWN0 aXZlX3ZjcHVfY291bnQ7CiAgICAgICAgICAgICB9CiAgICAgICAgICAgICBzZG9tLT53ZWlnaHQg PSBvcC0+dS5jcmVkaXQud2VpZ2h0OwogICAgICAgICB9CkBAIC05NzYsOSArOTc3LDkgQEAKICAg ICAgICAgQlVHX09OKCBpc19pZGxlX2RvbWFpbihzZG9tLT5kb20pICk7CiAgICAgICAgIEJVR19P Tiggc2RvbS0+YWN0aXZlX3ZjcHVfY291bnQgPT0gMCApOwogICAgICAgICBCVUdfT04oIHNkb20t PndlaWdodCA9PSAwICk7Ci0gICAgICAgIEJVR19PTiggc2RvbS0+d2VpZ2h0ID4gd2VpZ2h0X2xl ZnQgKTsKKyAgICAgICAgQlVHX09OKCAoc2RvbS0+d2VpZ2h0ICogc2RvbS0+YWN0aXZlX3ZjcHVf Y291bnQpID4gd2VpZ2h0X2xlZnQgKTsKIAotICAgICAgICB3ZWlnaHRfbGVmdCAtPSBzZG9tLT53 ZWlnaHQ7CisgICAgICAgIHdlaWdodF9sZWZ0IC09ICggc2RvbS0+d2VpZ2h0ICogc2RvbS0+YWN0 aXZlX3ZjcHVfY291bnQgKTsKIAogICAgICAgICAvKgogICAgICAgICAgKiBBIGRvbWFpbidzIGZh aXIgc2hhcmUgaXMgY29tcHV0ZWQgdXNpbmcgaXRzIHdlaWdodCBpbiBjb21wZXRpdGlvbgpAQCAt OTkxLDcgKzk5Miw5IEBACiAgICAgICAgIGNyZWRpdF9wZWFrID0gc2RvbS0+YWN0aXZlX3ZjcHVf Y291bnQgKiBDU0NIRURfQ1JFRElUU19QRVJfQUNDVDsKICAgICAgICAgaWYgKCBwcnYtPmNyZWRp dF9iYWxhbmNlIDwgMCApCiAgICAgICAgIHsKLSAgICAgICAgICAgIGNyZWRpdF9wZWFrICs9ICgg KCAtcHJ2LT5jcmVkaXRfYmFsYW5jZSAqIHNkb20tPndlaWdodCkgKworICAgICAgICAgICAgY3Jl ZGl0X3BlYWsgKz0gKCAoIC1wcnYtPmNyZWRpdF9iYWxhbmNlCisgICAgICAgICAgICAgICAgICAg ICAgICAgICAgICAgKiBzZG9tLT53ZWlnaHQKKyAgICAgICAgICAgICAgICAgICAgICAgICAgICAg ICAqIHNkb20tPmFjdGl2ZV92Y3B1X2NvdW50KSArCiAgICAgICAgICAgICAgICAgICAgICAgICAg ICAgICh3ZWlnaHRfdG90YWwgLSAxKQogICAgICAgICAgICAgICAgICAgICAgICAgICAgKSAvIHdl aWdodF90b3RhbDsKICAgICAgICAgfQpAQCAtMTAwMiwxMSArMTAwNSwxNSBAQAogICAgICAgICAg ICAgaWYgKCBjcmVkaXRfY2FwIDwgY3JlZGl0X3BlYWsgKQogICAgICAgICAgICAgICAgIGNyZWRp dF9wZWFrID0gY3JlZGl0X2NhcDsKIAorICAgICAgICAgICAgLyogRklYTUUgLS0gc2V0IGNhcCBw ZXItdmNwdSBhcyB3ZWxsLi4uPyAqLwogICAgICAgICAgICAgY3JlZGl0X2NhcCA9ICggY3JlZGl0 X2NhcCArICggc2RvbS0+YWN0aXZlX3ZjcHVfY291bnQgLSAxICkKICAgICAgICAgICAgICAgICAg ICAgICAgICApIC8gc2RvbS0+YWN0aXZlX3ZjcHVfY291bnQ7CiAgICAgICAgIH0KIAotICAgICAg ICBjcmVkaXRfZmFpciA9ICggKCBjcmVkaXRfdG90YWwgKiBzZG9tLT53ZWlnaHQpICsgKHdlaWdo dF90b3RhbCAtIDEpCisgICAgICAgIGNyZWRpdF9mYWlyID0gKCAoIGNyZWRpdF90b3RhbAorICAg ICAgICAgICAgICAgICAgICAgICAgICAqIHNkb20tPndlaWdodAorICAgICAgICAgICAgICAgICAg ICAgICAgICAqIHNkb20tPmFjdGl2ZV92Y3B1X2NvdW50ICkKKyAgICAgICAgICAgICAgICAgICAg ICAgICsgKHdlaWdodF90b3RhbCAtIDEpCiAgICAgICAgICAgICAgICAgICAgICAgKSAvIHdlaWdo dF90b3RhbDsKIAogICAgICAgICBpZiAoIGNyZWRpdF9mYWlyIDwgY3JlZGl0X3BlYWsgKQo= --0015175cdc26633c63048da2e0ee Content-Type: text/plain; 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