Changeset 478 for soft/giet_vm/giet_kernel/sys_handler.h

Timestamp:

Jan 1, 2015, 7:58:56 PM (10 years ago)

Author:

alain

Message:

1) The chained buffer structure has been modified to have one single buffer descriptor per cache line (64 bytes),
in order to simplify the software cache coherence between L2 and L3 caches when the IO bridge is used.
A new buffer_descriptor_t structure has been defined, and the fbf_chbuf_t and nic_chbuf_t structures have been adapted.
2) The NIC related system call handler _sys_nic_start() and _sys_nic_move() have been modified to support a distributed
kernel chbuf (one 4 Kbytes buffer per cluster), in order to support the one Gbit Ethernet NIC controller throughput.

• the _sys_nic_start() function initialises the distributed chbuf, using the distributed heap.
• the _sys_nic_move() function transfer one 4 KBytes container from the local kernel chbuf to an user local buffer.

This approach has been validated on the "classif" application: no packet loss with 16 clusters for average packet
length = 600 bytes and inter-packet gap = 300 cycles.

File:

• soft/giet_vm/giet_kernel/sys_handler.h (modified) (3 diffs)

soft/giet_vm/giet_kernel/sys_handler.h

@@ -16 +16 @@
 #include "locks.h"
 
-#if !defined ( GIET_NIC_NBUFS )
-# error: You must define GIET_NIC_NBUFS in the giet_config.h file
-#endif
-
-#if !defined ( GIET_NIC_NFAKE )
-# error: You must define GIET_NIC_NFAKE in the giet_config.h file
-#endif
-
-#if !defined ( GIET_NIC_BUFSIZE )
-# error: You must define GIET_NIC_BUFSIZE in the giet_config.h file
-#endif
-
-#if !defined ( GIET_NIC_TIMEOUT )
-# error: You must define GIET_NIC_TIMEOUT in the giet_config.h file
-#endif
-
-#if !defined ( GIET_NIC_MAC4 )
-# error: You must define GIET_NIC_MAC4 in the giet_config.h file
-#endif
-
-#if !defined ( GIET_NIC_MAC2 )
-# error: You must define GIET_NIC_MAC2 in the giet_config.h file
-#endif
-
-#if ( (GIET_NIC_NBUFS + GIET_NIC_NFAKE) % 8 )
-#error: GIET_NIC_NBUFS + GIET_NIC_NFAKE must be multiple of 8 for alignment
-#endif
-
 ///////////////////////////////////////////////////////////////////////////////////
 //     Syscall Vector Table (indexed by syscall index)
@@ -51 +23 @@
 
 ///////////////////////////////////////////////////////////////////////////////////
+// This structure is used by the nic_chbuf_t and fbf_chbuf_t structures.
+// It describes a single buffer descriptor. The useful information is contained
+// in one single 64 bits word (desc field): 
+// - the 48 LSB bits contain the buffer physical address
+// - the MSB bit 63 indicates the buffer state (empty if 0)
+// This descriptor must be aligned on a cache line (64 bytes) to simplify 
+// the software L2/L3 cache coherence when the IO bridge is used. 
+///////////////////////////////////////////////////////////////////////////////////
+
+typedef struct buffer_descriptor_s
+{
+    unsigned long long  desc;
+    unsigned int        padding[14];
+} buffer_descriptor_t;
+ 
+///////////////////////////////////////////////////////////////////////////////////
 // This structure is used by the CMA component to move a stream 
-// of images from two buffers in user space to the frame buffer in kernel space.
+// of images from two user buffers to the frame buffer in kernel space.
 // it must be 64 bytes aligned.
 // It contains two chbuf arrays:
-// - The SRC chbuf contains two buffers (buf0 & buf1), that can be in user space.
+// - The SRC chbuf contains two buffers (buf0 & buf1), in user space.
 // - The DST cbuf contains one single buffer (fbf), that is the frame buffer.
 // - The length field define the buffer size (bytes)
@@ -62 +50 @@
 typedef struct fbf_chbuf_s
 {
-    unsigned long long  buf0;        // physical address + status for user buffer 0 
-    unsigned long long  buf1;        // physical address + status for user buffer 1
-    unsigned long long  fbf;         // physical address + status for user buffer 0 
-    unsigned int        length;      // buffer length (bytes)
-    unsigned int        padding[9];  // padding for 64 bytes alignment
+    buffer_descriptor_t  buf0;         // first user buffer descriptor 
+    buffer_descriptor_t  buf1;         // second user buffer descriptor
+    buffer_descriptor_t  fbf;          // frame buffer descriptor 
+    unsigned int         length;       // buffer length (bytes)
+    unsigned int         padding[15];  // padding for 64 bytes alignment
 } fbf_chbuf_t;   
 
 //////////////////////////////////////////////////////////////////////////////////
-// This structure is used by the CMA component to move a stream
-// of packet containers between the NIC component an a chbuf containing
-// a variable number of buffers in kernel space.
+// This structure is used by the CMA component to move a stream of containers 
+// between the NIC chbuf containing 2 buffers, and a kernel chbuf 
+// containing (X_SIZE * Y_SIZE) buffers (one buffer per cluster).
 // The same structure is used for both TX or RX transfers.
 // It must be 64 bytes aligned.
-// The single buffer size and the number of buffers must be defined by the 
-// GIET_NIC_BUFSIZE and GIET_NIC_NBUFS parameters in giet_config.h.
-// - The buffer array implements the chbuf, and is concurently accessed 
-//   by the CMA component and by the kernel code.
-// - The lock must be taken by the kernel code, because several user tasks
-//   can concurently try to consume buffers in the chbuf.
-// - The index is only used by the kernel, and define the currently pointed 
-//   buffer for read (RX transfer) or write (TX transfer).
 //////////////////////////////////////////////////////////////////////////////////
 
 typedef struct nic_chbuf_s
 {
-    unsigned long long  buffer[GIET_NIC_NBUFS];  // Kernel chbuf
-    unsigned long long  unused[GIET_NIC_NFAKE];  // padding for 64 bytes alignment
-    unsigned int        index;                   // current buffer index
-    unsigned int        padding[15];             // padding for 64 bytes alignment
+    buffer_descriptor_t  buffer[X_SIZE*Y_SIZE];  // kernel chbuf
 } nic_chbuf_t;
-
 
 //////////////////////////////////////////////////////////////////////////////////