The patch introduces yet another runqueue arrangement option for Credit2. In fact, it allows the user to specify, explicitly and precisely, what pCPUs should belong to which runqueue.
Signed-off-by: Dario Faggioli <dario.faggi...@citrix.com> Signed-off-by: Praveen Kumar <kpraveen.l...@gmail.com> --- Cc: George Dunlap <george.dun...@eu.citrix.com> Cc: Praveen Kumar <kpraveen.l...@gmail.com> --- This is derived --although *heavily* reworked-- from what Praveen has submitted before, here: https://lists.xen.org/archives/html/xen-devel/2017-04/msg02402.html https://lists.xen.org/archives/html/xen-devel/2017-06/msg00201.html During my review of that, I suggested to make the array dynamically allocated, using nr_cpu_ids as its size. Turns out, that does not make much sense, as at the time the parameters are parsed, nr_cpu_ids is still equal to NR_CPUS. --- docs/misc/xen-command-line.markdown | 12 +++ xen/common/sched_credit2.c | 135 +++++++++++++++++++++++++++++++++++ 2 files changed, 146 insertions(+), 1 deletion(-) diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown index 9797c8d..dbf5d4c 100644 --- a/docs/misc/xen-command-line.markdown +++ b/docs/misc/xen-command-line.markdown @@ -567,7 +567,7 @@ also slow in responding to load changes. The default value of `1 sec` is rather long. ### credit2\_runqueue -> `= cpu | core | socket | node | all` +> `= cpu | core | socket | node | all | <custom>` > Default: `socket` @@ -585,6 +585,16 @@ Available alternatives, with their meaning, are: * `node`: one runqueue per each NUMA node of the host; * `all`: just one runqueue shared by all the logical pCPUs of the host +* `<custom>`: one runqueue per each specified subset of logical + pCPUs of the host. Subsets are defined either as: + `[[0,1,][2,6][3,5][4,7]]`, or as: + `'0,1;2,6;3,5;4,7'`. That means + - pCPUs 0 and 1 belong to runqueue 0 + - pCPUs 2 and 6 belong to runqueue 1 + - pCPUs 3 and 5 belong to runqueue 2 + - pCPUs 4 and 7 belong to runqueue 3 + pCPUs that are present on the host, but are not + part of any subset, are assigned to runqueue 0. ### dbgp > `= ehci[ <integer> | @pci<bus>:<slot>.<func> ]` diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c index 0f93ad5..10da084 100644 --- a/xen/common/sched_credit2.c +++ b/xen/common/sched_credit2.c @@ -12,6 +12,7 @@ #include <xen/init.h> #include <xen/lib.h> +#include <xen/ctype.h> #include <xen/sched.h> #include <xen/domain.h> #include <xen/delay.h> @@ -323,6 +324,17 @@ integer_param("credit2_balance_over", opt_overload_balance_tolerance); * (logical) processors of the host belong. This will happen if * the opt_runqueue parameter is set to 'all'. * + * - custom: meaning that there will be one runqueue per each specified + * subset, as shown in the following examples: + * - credit2_runqueue=[[0,1][3][4,5]] + * - credit2_runqueue='0,1;3;4,5' + * These (both) mean the following: + * - CPU 0 and CPU 1 belong to runqueue 0 + * - CPU 3 belongs to runqueue 1 + * - CPU 4 and CPU 5 belong to runqueue 2 + * CPUs that are present on the host, but are not part of any + * defined subset, will be assigned to runqueue 0. + * * Depending on the value of opt_runqueue, therefore, cpus that are part of * either the same physical core, the same physical socket, the same NUMA * node, or just all of them, will be put together to form runqueues. @@ -332,6 +344,7 @@ integer_param("credit2_balance_over", opt_overload_balance_tolerance); #define OPT_RUNQUEUE_SOCKET 2 #define OPT_RUNQUEUE_NODE 3 #define OPT_RUNQUEUE_ALL 4 +#define OPT_RUNQUEUE_CUSTOM 5 static const char *const opt_runqueue_str[] = { [OPT_RUNQUEUE_CPU] = "cpu", [OPT_RUNQUEUE_CORE] = "core", @@ -341,6 +354,115 @@ static const char *const opt_runqueue_str[] = { }; static int __read_mostly opt_runqueue = OPT_RUNQUEUE_SOCKET; +static unsigned int __read_mostly custom_cpu_runqueue[NR_CPUS]; + +static int parse_custom_runqueue(const char *s) +{ + unsigned int cpu, rqi = 0; + bool in_subset = false, ret = true; + cpumask_t cpus; + + /* + * If we are dealing with format 1 (i.e., [[0,1][3,5]]), first + * and last character must be '[' and ']', respectively. + * + * If we are dealing with format 2 (i.e., 0,1;3,5), first and + * last character must be numbers. + */ + if ( *s == '[' && *(s+strlen(s)-1) == ']' ) + s++; + else if ( !(isdigit(*s) && isdigit(s[strlen(s)-1])) ) + return false; + + cpumask_clear(&cpus); + while ( !(*s == ']' && *(s+1) == '\0') && *s != '\0' ) + { + /* + * We tolerate only the allowed characters (depending on the + * format). Also, we don't accept empty subsets. + */ + if ( *(s+strlen(s)-1) == ']' ) + { + /* Format 1 */ + if ( !(*s == '[' || *s == ']' || *s == ',' || isdigit(*s)) || + (*s == '[' && *(s+1) == ']') ) + return false; + } + else + { + /* Format 2 */ + if ( !(*s == ';' || *s == ',' || isdigit(*s)) || + (*s == ';' && *(s+1) == ';') ) + return false; + } + + /* Are we at the beginning of a subset, in format 1? */ + if ( *s == '[' ) + { + /* + * If we are opening a subset, we must have closed all the + * previously defined ones, or the string is malformed. + */ + if ( in_subset ) + return false; + + s++; + in_subset = true; + continue; + } + /* Are we at the end of a subset? */ + if ( *s == ']' || *s == ';' ) + { + /* + * If we are closing a subset, in format 1, we must have + * opened it before. If not, the string is malformed. + */ + if ( *s == ']' && !in_subset ) + return false; + + s++; + rqi++; + in_subset = false; + continue; + } + + /* + * At this point, we must be dealing with either a CPU ID (i.e., + * a number) or CPU separator, within a subset (i.e., ','). + */ + if ( *s == ',' ) + { + s++; + continue; + } + cpu = simple_strtoul(s, &s, 10); + + /* Is the cpu ID we found valid? */ + if ( cpu >= nr_cpu_ids ) + return false; + + /* + * CPU IDs are considered only the first time they're found in the + * string considere. Multiple subsequent occurrences are ignored. + */ + if ( cpumask_test_cpu(cpu, &cpus) ) + continue; + + cpumask_set_cpu(cpu, &cpus); + custom_cpu_runqueue[cpu] = rqi; + } + + /* + * If in_subset is true, it means we are in format 1, and we + * found a subset that was not closed with its ']', which + * means the string is malformed. + */ + if ( in_subset ) + return false; + + return ret; +} + static int parse_credit2_runqueue(const char *s) { unsigned int i; @@ -354,6 +476,13 @@ static int parse_credit2_runqueue(const char *s) } } + if ( parse_custom_runqueue(s) ) + { + opt_runqueue = OPT_RUNQUEUE_CUSTOM; + return 0; + } + + printk("WARNING, unrecognized value of credit2_runqueue option!\n"); return -EINVAL; } custom_param("credit2_runqueue", parse_credit2_runqueue); @@ -728,6 +857,12 @@ cpu_to_runqueue(struct csched2_private *prv, unsigned int cpu) struct csched2_runqueue_data *rqd; unsigned int rqi; + if ( opt_runqueue == OPT_RUNQUEUE_CUSTOM ) + { + ASSERT(custom_cpu_runqueue[cpu] < nr_cpu_ids); + return custom_cpu_runqueue[cpu]; + } + for ( rqi = 0; rqi < nr_cpu_ids; rqi++ ) { unsigned int peer_cpu; _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
