seastar::scheduling_group Class Reference

Detailed Description

Identifies function calls that are accounted as a group.

A scheduling_group is a tag that can be used to mark a function call. Executions of such tagged calls are accounted as a group.

#include <seastar/core/scheduling.hh>

Public Member Functions
constexpr	scheduling_group () noexcept
	Creates a scheduling_group object denoting the default group.
bool	active () const noexcept
const sstring &	name () const noexcept
const sstring &	short_name () const noexcept
bool	operator== (scheduling_group x) const noexcept
bool	operator!= (scheduling_group x) const noexcept
bool	is_main () const noexcept
bool	is_at_exit () const noexcept
template<typename T >
T &	get_specific (scheduling_group_key key) noexcept
void	set_shares (float shares) noexcept
float	get_shares () const noexcept
future	update_io_bandwidth (uint64_t bandwidth) const
	Updates the current IO bandwidth for a given scheduling group. More...

Member Function Documentation

get_shares()

float seastar::scheduling_group::get_shares ( ) const

noexcept

Returns the number of shares the group has

Similarly to the set_shares, the returned value is only relevant to the calling shard

get_specific()

template<typename T >

T& seastar::scheduling_group::get_specific ( scheduling_group_key  key )

inlinenoexcept

Returnes a reference to this scheduling group specific value

Template Parameters

T	- the type of the scheduling specific type (cannot be deduced)

Parameters

key	- the key of the value to retrieve.

Returns

A reference to this scheduling specific value.

set_shares()

void seastar::scheduling_group::set_shares ( float  shares )

noexcept

Adjusts the number of shares allotted to the group.

Dynamically adjust the number of shares allotted to the group, increasing or decreasing the amount of CPU bandwidth it gets. The adjustment is local to the shard.

This can be used to reduce a background job's interference with a foreground load: the shares can be started at a low value, increased when the background job's backlog increases, and reduced again when the backlog decreases.

Parameters

shares

number of shares allotted to the group. Use numbers in the 1-1000 range.

update_io_bandwidth()

future seastar::scheduling_group::update_io_bandwidth

(

uint64_t

bandwidth

)

const

Updates the current IO bandwidth for a given scheduling group.

The bandwidth applied is NOT shard-local, instead it is applied so that all shards cannot consume more bytes-per-second altogether

Parameters

bandwidth

the new bandwidth value in bytes/second

Returns

a future that is ready when the bandwidth update is applied

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The documentation for this class was generated from the following file:

• seastar/core/scheduling.hh