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serenity/Kernel/Storage/NVMe/NVMePollQueue.cpp
Pankaj Raghav d234e6b801 Kernel: Add polling support to NVMe
Add polling support to NVMe so that it does not use interrupt to
complete a IO but instead actively polls for completion. This probably
is not very efficient in terms of CPU usage but it does not use
interrupts to complete a IO which is beneficial at the moment as there
is no MSI(X) support and it can reduce the latency of an IO in a very
fast NVMe device.

The NVMeQueue class has been made the base class for NVMeInterruptQueue
and NVMePollQueue. The factory function `NVMeQueue::try_create` will
return the appropriate queue to the controller based on the polling
boot parameter.

The polling mode can be enabled by adding an extra boot parameter:
`nvme_poll`.
2022-02-02 18:26:59 +01:00

44 lines
1.6 KiB
C++

/*
* Copyright (c) 2022, Pankaj R <pankydev8@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "NVMePollQueue.h"
#include "Kernel/Arch/x86/IO.h"
#include "Kernel/Devices/BlockDevice.h"
#include "NVMeDefinitions.h"
namespace Kernel {
UNMAP_AFTER_INIT NVMePollQueue::NVMePollQueue(NonnullOwnPtr<Memory::Region> rw_dma_region, Memory::PhysicalPage const& rw_dma_page, u16 qid, u32 q_depth, OwnPtr<Memory::Region> cq_dma_region, NonnullRefPtrVector<Memory::PhysicalPage> cq_dma_page, OwnPtr<Memory::Region> sq_dma_region, NonnullRefPtrVector<Memory::PhysicalPage> sq_dma_page, Memory::TypedMapping<volatile DoorbellRegister> db_regs)
: NVMeQueue(move(rw_dma_region), rw_dma_page, qid, q_depth, move(cq_dma_region), cq_dma_page, move(sq_dma_region), sq_dma_page, move(db_regs))
{
}
void NVMePollQueue::submit_sqe(NVMeSubmission& sub)
{
NVMeQueue::submit_sqe(sub);
SpinlockLocker lock_cq(m_cq_lock);
while (!process_cq()) {
IO::delay(1);
}
}
void NVMePollQueue::complete_current_request(u16 status)
{
auto current_request = m_current_request;
m_current_request.clear();
if (status) {
current_request->complete(AsyncBlockDeviceRequest::Failure);
return;
}
if (current_request->request_type() == AsyncBlockDeviceRequest::RequestType::Read) {
if (auto result = current_request->write_to_buffer(current_request->buffer(), m_rw_dma_region->vaddr().as_ptr(), 512 * current_request->block_count()); result.is_error()) {
current_request->complete(AsyncDeviceRequest::MemoryFault);
return;
}
}
current_request->complete(AsyncDeviceRequest::Success);
return;
}
}