Linux Socket channel set options: can't sc.socket().setSendBufferSize(x);

The attached test case passes on Windows and Solaris, but
fails on linux platforms. (tested on redhat 6.2, turbo linux,
mandrake 7.1).

excerpt from test:
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InetSocketAddress isa
= new InetSocketAddress(InetAddress.getByName(HOST),
PORT);
SocketChannel sc = SocketChannel.open();
//get default sendBufferSize
int y = sc.socket().getSendBufferSize();
       System.out.println(" default buffer size = " + y);

for (int x = 1; x < 1000; x++) {
sc.socket().setSendBufferSize(x);
if (sc.socket().getSendBufferSize() != x) {
failures++;
System.out.println("testcase#3 failed setSendBufferSize");
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