From 4371b2fe70f612f1a0e838dc1d76f04623734934 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Fabian=20Gr=C3=BCnbichler?= Date: Mon, 9 Oct 2017 10:14:57 +0200 Subject: [PATCH] qm.adoc: style/grammar --- qm.adoc | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/qm.adoc b/qm.adoc index 157e4e8..eda85f8 100644 --- a/qm.adoc +++ b/qm.adoc @@ -170,7 +170,7 @@ either the *raw disk image format* or the *QEMU image format*. thin provisioning of the disk image. * the *raw disk image* is a bit-to-bit image of a hard disk, similar to what you would get when executing the `dd` command on a block device in Linux. This - format do not support thin provisioning or snapshots by itself, requiring + format does not support thin provisioning or snapshots by itself, requiring cooperation from the storage layer for these tasks. It may, however, be up to 10% faster than the *QEMU image format*. footnote:[See this benchmark for details http://events.linuxfoundation.org/sites/events/files/slides/CloudOpen2013_Khoa_Huynh_v3.pdf] @@ -243,13 +243,13 @@ cost of context switches. Resource Limits ^^^^^^^^^^^^^^^ -Additional, to the count of virtual cores, you can configure how much resources +In addition to the number of virtual cores, you can configure how much resources a VM can get in relation to the host CPU time and also in relation to other VMs. With the *cpulimit* (`Host CPU Time') option you can limit how much CPU time the whole VM can use on the host. It is a floating point value representing CPU time in percent, so `1.0` is equal to `100%`, `2.5` to `250%` and so on. If a -single process would fully use one single core he would have `100%` CPU Time +single process would fully use one single core it would have `100%` CPU Time usage. If a VM with four cores utilizes all its cores fully it would theoretically use `400%`. In reality the usage may be even a bit higher as Qemu can have additional threads for VM peripherals besides the vCPU core ones. @@ -326,19 +326,19 @@ vCPU hot-plug ^^^^^^^^^^^^^ Modern operating systems introduced the capability to hot-plug and, to a -certain extent, hot-unplug CPU in a running systems. With Virtualisation we -have even the luck that we avoid a lot of (physical) problem from real -hardware. -But it is still a complicated and not always well tested feature, so its use -should be restricted to cases where its absolutely needed. Its uses can be -replicated with other, well tested and less complicated, features, see +certain extent, hot-unplug CPUs in a running systems. Virtualisation allows us +to avoid a lot of the (physical) problems real hardware can cause in such +scenarios. +Still, this is a rather new and complicated feature, so its use should be +restricted to cases where its absolutely needed. Most of the functionality can +be replicated with other, well tested and less complicated, features, see xref:qm_cpu_resource_limits[Resource Limits]. In {pve} the maximal number of plugged CPUs is always `cores * sockets`. To start a VM with less than this total core count of CPUs you may use the -*vpus* setting, it denotes how many vCPUs should be plugged at VM start. +*vpus* setting, it denotes how many vCPUs should be plugged in at VM start. -Currently only Linux is working OK with this feature, a kernel newer than 3.10 +Currently only this feature is only supported on Linux, a kernel newer than 3.10 is needed, a kernel newer than 4.7 is recommended. You can use a udev rule as follow to automatically set new CPUs as online in -- 2.39.2