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Kernel: Avoid allocations for Select vectors by using inline capacity

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Good tip by Andreas :)
This commit is contained in:
Robin Burchell 2019-07-19 09:04:12 +02:00 • committed by Andreas Kling
parent 52743f9eec
commit 750dbe986d
3 changed files with 13 additions and 11 deletions
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12
Kernel/Process.cpp
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@ -1798,9 +1798,9 @@ int Process::sys$select(const Syscall::SC_select_params* params)
select_has_timeout = true; select_has_timeout = true;
} }
Vector<int> rfds; Thread::SelectBlocker::FDVector rfds;
Vector<int> wfds; Thread::SelectBlocker::FDVector wfds;
Vector<int> efds; Thread::SelectBlocker::FDVector efds;
auto transfer_fds = [&](auto* fds, auto& vector) -> int { auto transfer_fds = [&](auto* fds, auto& vector) -> int {
vector.clear_with_capacity(); vector.clear_with_capacity();
@ -1852,8 +1852,8 @@ int Process::sys$poll(pollfd* fds, int nfds, int timeout)
if (!validate_read_typed(fds)) if (!validate_read_typed(fds))
return -EFAULT; return -EFAULT;
Vector<int> rfds; Thread::SelectBlocker::FDVector rfds;
Vector<int> wfds; Thread::SelectBlocker::FDVector wfds;
for (int i = 0; i < nfds; ++i) { for (int i = 0; i < nfds; ++i) {
if (fds[i].events & POLLIN) if (fds[i].events & POLLIN)
@ -1882,7 +1882,7 @@ int Process::sys$poll(pollfd* fds, int nfds, int timeout)
#endif #endif
if (has_timeout|| timeout < 0) if (has_timeout|| timeout < 0)
current->block(*new Thread::SelectBlocker(actual_timeout, has_timeout, rfds, wfds, Vector<int>())); current->block(*new Thread::SelectBlocker(actual_timeout, has_timeout, rfds, wfds, Thread::SelectBlocker::FDVector()));
int fds_with_revents = 0; int fds_with_revents = 0;

2
Kernel/Scheduler.cpp
View file

@ -143,7 +143,7 @@ bool Thread::SleepBlocker::should_unblock(Thread&, time_t, long)
return m_wakeup_time <= g_uptime; return m_wakeup_time <= g_uptime;
} }
Thread::SelectBlocker::SelectBlocker(const timeval& tv, bool select_has_timeout, const Vector<int>& read_fds, const Vector<int>& write_fds, const Vector<int>& except_fds) Thread::SelectBlocker::SelectBlocker(const timeval& tv, bool select_has_timeout, const FDVector& read_fds, const FDVector& write_fds, const FDVector& except_fds)
: m_select_timeout(tv) : m_select_timeout(tv)
, m_select_has_timeout(select_has_timeout) , m_select_has_timeout(select_has_timeout)
, m_select_read_fds(read_fds) , m_select_read_fds(read_fds)

10
Kernel/Thread.h
View file

@ -10,6 +10,7 @@
#include <Kernel/KResult.h> #include <Kernel/KResult.h>
#include <Kernel/UnixTypes.h> #include <Kernel/UnixTypes.h>
#include <Kernel/VM/Region.h> #include <Kernel/VM/Region.h>
#include <LibC/fd_set.h>
class Alarm; class Alarm;
class FileDescription; class FileDescription;
@ -135,15 +136,16 @@ public:
class SelectBlocker : public Blocker { class SelectBlocker : public Blocker {
public: public:
SelectBlocker(const timeval& tv, bool select_has_timeout, const Vector<int>& read_fds, const Vector<int>& write_fds, const Vector<int>& except_fds); typedef Vector<int, FD_SETSIZE> FDVector;
SelectBlocker(const timeval& tv, bool select_has_timeout, const FDVector& read_fds, const FDVector& write_fds, const FDVector& except_fds);
virtual bool should_unblock(Thread&, time_t, long) override; virtual bool should_unblock(Thread&, time_t, long) override;
private: private:
timeval m_select_timeout; timeval m_select_timeout;
bool m_select_has_timeout { false }; bool m_select_has_timeout { false };
const Vector<int>& m_select_read_fds; const FDVector& m_select_read_fds;
const Vector<int>& m_select_write_fds; const FDVector& m_select_write_fds;
const Vector<int>& m_select_exceptional_fds; const FDVector& m_select_exceptional_fds;
}; };
class WaitBlocker : public Blocker { class WaitBlocker : public Blocker {