source: libcfa/src/concurrency/io/types.hfa@ e71e94a

//
// Cforall Version 1.0.0 Copyright (C) 2020 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// io/types.hfa -- PRIVATE
// Types used by the I/O subsystem
//
// Author           : Thierry Delisle
// Created On       : Fri Jul 31 16:22:47 2020
// Last Modified By :
// Last Modified On :
// Update Count     :
//

#pragma once

extern "C" {
        #include <linux/types.h>
}

#include "bits/locks.hfa"
#include "bits/queue.hfa"
#include "iofwd.hfa"
#include "kernel/fwd.hfa"
#include "limits.hfa"

#if defined(CFA_HAVE_LINUX_IO_URING_H)
        #include "bits/sequence.hfa"
        #include "monitor.hfa"

        struct processor;
        monitor $io_arbiter;

        //-----------------------------------------------------------------------
        // Ring Data structure
      struct __sub_ring_t {
                struct {
                        // Head and tail of the ring (associated with array)
                        volatile __u32 * head;   // one passed last index consumed by the kernel
                        volatile __u32 * tail;   // one passed last index visible to the kernel
                        volatile __u32 released; // one passed last index released back to the free list

                        // The actual kernel ring which uses head/tail
                        // indexes into the sqes arrays
                        __u32 * array;
                } kring;

                struct {
                        volatile __u32 head;
                        volatile __u32 tail;
                        // The ring which contains free allocations
                        // indexes into the sqes arrays
                        __u32 * array;
                } free_ring;

                // number of sqes to submit on next system call.
                __u32 to_submit;

                // number of entries and mask to go with it
                const __u32 * num;
                const __u32 * mask;

                // Submission flags, currently only IORING_SETUP_SQPOLL
                __u32 * flags;

                // number of sqes not submitted
                // From documentation : [dropped] is incremented for each invalid submission queue entry encountered in the ring buffer.
                __u32 * dropped;

                // A buffer of sqes (not the actual ring)
                struct io_uring_sqe * sqes;

                // The location and size of the mmaped area
                void * ring_ptr;
                size_t ring_sz;
        };

        struct __cmp_ring_t {
                volatile bool lock;

                unsigned id;

                unsigned long long ts;

                // Head and tail of the ring
                volatile __u32 * head;
                volatile __u32 * tail;

                // number of entries and mask to go with it
                const __u32 * mask;
                const __u32 * num;

                // I don't know what this value is for
                __u32 * overflow;

                // the kernel ring
                volatile struct io_uring_cqe * cqes;

                // The location and size of the mmaped area
                void * ring_ptr;
                size_t ring_sz;
        };

        struct __outstanding_io {
                inline Colable;
                single_sem sem;
        };
        static inline __outstanding_io *& Next( __outstanding_io * n ) { return (__outstanding_io *)Next( (Colable *)n ); }

        struct __outstanding_io_queue {
                __spinlock_t lock;
                Queue(__outstanding_io) queue;
                volatile bool empty;
        };

        struct __external_io {
                inline __outstanding_io;
                __u32 * idxs;
                __u32 have;
                bool lazy;
        };


        struct __attribute__((aligned(128))) $io_context {
                $io_arbiter * arbiter;
                processor * proc;

                __outstanding_io_queue ext_sq;

                struct __sub_ring_t sq;
                struct __cmp_ring_t cq;
                __u32 ring_flags;
                int fd;
        };

        static inline unsigned long long ts($io_context *& this) {
                const __u32 head = *this->cq.head;
                const __u32 tail = *this->cq.tail;

                if(head == tail) return MAX;

                return this->cq.ts;
        }

        struct __pending_alloc {
                inline __outstanding_io;
                __u32 * idxs;
                __u32 want;
                $io_context * ctx;
        };

        struct __attribute__((aligned(128))) $io_arbiter {
                __outstanding_io_queue pending;
        };

        //-----------------------------------------------------------------------
        // Misc
        // Weirdly, some systems that do support io_uring don't actually define these
        #ifdef __alpha__
                /*
                * alpha is the only exception, all other architectures
                * have common numbers for new system calls.
                */
                #ifndef __NR_io_uring_setup
                        #define __NR_io_uring_setup           535
                #endif
                #ifndef __NR_io_uring_enter
                        #define __NR_io_uring_enter           536
                #endif
                #ifndef __NR_io_uring_register
                        #define __NR_io_uring_register        537
                #endif
        #else /* !__alpha__ */
                #ifndef __NR_io_uring_setup
                        #define __NR_io_uring_setup           425
                #endif
                #ifndef __NR_io_uring_enter
                        #define __NR_io_uring_enter           426
                #endif
                #ifndef __NR_io_uring_register
                        #define __NR_io_uring_register        427
                #endif
        #endif

        // void __ioctx_prepare_block($io_context & ctx);
#endif