Andreas Sandberg has uploaded this change for review. (
https://gem5-review.googlesource.com/2226
Change subject: dma, kvm: Bypassing DMA in KVM execution mode
......................................................................
dma, kvm: Bypassing DMA in KVM execution mode
Event-free fast write operation to the DMA buffer during KVM
exeecution mode.
Change-Id: I5b378c2fb6a1d3e687cef15e807e63a0a53a60e2
Reviewed-by: Andreas Sandberg <[email protected]>
---
M src/dev/dma_device.cc
M src/dev/dma_device.hh
2 files changed, 44 insertions(+), 10 deletions(-)
diff --git a/src/dev/dma_device.cc b/src/dev/dma_device.cc
index 3515e70..f84b4c3 100644
--- a/src/dev/dma_device.cc
+++ b/src/dev/dma_device.cc
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2012, 2015 ARM Limited
+ * Copyright (c) 2012, 2015, 2017 ARM Limited
* All rights reserved.
*
* The license below extends only to copyright in the software and shall
@@ -50,6 +50,7 @@
#include "base/chunk_generator.hh"
#include "debug/DMA.hh"
#include "debug/Drain.hh"
+#include "mem/port_proxy.hh"
#include "sim/system.hh"
DmaPort::DmaPort(MemObject *dev, System *s)
@@ -371,6 +372,40 @@
return;
const bool old_eob(atEndOfBlock());
+
+ if (port.sys->bypassCaches())
+ resumeFillFunctional();
+ else
+ resumeFillTiming();
+
+ if (!old_eob && atEndOfBlock())
+ onEndOfBlock();
+}
+
+void
+DmaReadFifo::resumeFillFunctional()
+{
+ const size_t fifo_space = buffer.capacity() - buffer.size();
+ const size_t kvm_watermark = port.sys->cacheLineSize();
+ if (fifo_space >= kvm_watermark || buffer.capacity() < kvm_watermark) {
+ const size_t block_remaining = endAddr - nextAddr;
+ const size_t xfer_size = std::min(fifo_space, block_remaining);
+ std::vector<uint8_t> tmp_buffer(xfer_size);
+
+ assert(pendingRequests.empty());
+ DPRINTF(DMA, "KVM Bypassing startAddr=%#x xfer_size=%#x " \
+ "fifo_space=%#x block_remaining=%#x\n",
+ nextAddr, xfer_size, fifo_space, block_remaining);
+
+ port.sys->physProxy.readBlob(nextAddr, tmp_buffer.data(),
xfer_size);
+ buffer.write(tmp_buffer.begin(), xfer_size);
+ nextAddr += xfer_size;
+ }
+}
+
+void
+DmaReadFifo::resumeFillTiming()
+{
size_t size_pending(0);
for (auto &e : pendingRequests)
size_pending += e->requestSize();
@@ -392,11 +427,6 @@
pendingRequests.emplace_back(std::move(event));
}
-
- // EOB can be set before a call to dmaDone() if in-flight accesses
- // have been canceled.
- if (!old_eob && atEndOfBlock())
- onEndOfBlock();
}
void
@@ -429,8 +459,6 @@
if (pendingRequests.empty())
signalDrainDone();
}
-
-
DrainState
DmaReadFifo::drain()
diff --git a/src/dev/dma_device.hh b/src/dev/dma_device.hh
index 4e66b34..4a1946a 100644
--- a/src/dev/dma_device.hh
+++ b/src/dev/dma_device.hh
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2012-2013, 2015 ARM Limited
+ * Copyright (c) 2012-2013, 2015, 2017 ARM Limited
* All rights reserved.
*
* The license below extends only to copyright in the software and shall
@@ -494,9 +494,15 @@
/** Handle pending requests that have been flagged as done. */
void handlePending();
- /** Try to issue new DMA requests */
+ /** Try to issue new DMA requests or bypass DMA requests*/
void resumeFill();
+ /** Try to issue new DMA requests during normal execution*/
+ void resumeFillTiming();
+
+ /** Try to bypass DMA requests in KVM execution mode */
+ void resumeFillFunctional();
+
private: // Internal state
Fifo<uint8_t> buffer;
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I5b378c2fb6a1d3e687cef15e807e63a0a53a60e2
Gerrit-Change-Number: 2226
Gerrit-PatchSet: 1
Gerrit-Owner: Andreas Sandberg <[email protected]>
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