Hi, > John Williams wrote: > > That's the primary entry point for the upper network layer > > to send a > > packet via this device. The alignment requirement is deeply > > ingrained > > into the kernel. The problem comes about because ethernet > > frame headers > > are not a multiple of 4 bytes long, but kernel expects (or at least > > assumes) that IP header fields are word aligned. Here are 2 patches, applying both of them makes xenet_FifoSend() much faster. Patch skbuff.c.diff makes the data aligned for xenet_FifoSend(), patch adapter.c.diff checks the alignment and avoids memcpy() in case of that it's aligned. Patch skbuff.c.diff slows down tpc.c:tcp_sendmsg() because the memcpy() there has offset=2 now, but the second memcpy() which had offset=2 anyway is completely prevented now. So after all it's better now. What do you think about these 2 patches? My user program was permanently sending data. Time measuring with an oscilloscop showed that most of the time the spent time in xenet_FifoSend() is reduced from about 600us to about 200us. The 200us consists of 100us checksum calculation plus 100us spent in XEmac_FifoSend(). Though I noticed that the call of xenet_FifoSend() is just every millisecond. That is why the data throughput (Megabytes per second) to my PC keeps the same. Is xenet_FifoSend() called by a timer with such frequency of 1/ms? If yes, can it be reduced? CU, F@lk
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skbuff.c.diff
Description: skbuff.c.diff
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adapter.c.diff
Description: adapter.c.diff