From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mahesh Kumar Date: Mon, 28 Jul 2008 16:11:13 -0700 Subject: [ath9k-devel] Atheros Throughput with Aggregation & Encryption Message-ID: <488E5211.8010105@solectek.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ath9k-devel@lists.ath9k.org Hello, We have a critical issue in getting the high throughput, once we enable both the Aggregation (AMPDU) and Encryption (WPA) at the same time. (We are using the AR9160 chipset.) Our test setup is like this, [PC1] ---> [Access Point] --> [Client] --> [PC2]. We are sending a 100 Mbps of UDP traffic from PC1 to PC2. The Aggregation (AMPDU) & Encryption are enabled on both "Access point" and the "Client". Very low traffic ( < 1Mbps) is reaching at the PC2, that also occasionally. Most of the traffic is dropped at the Access point itself. When we check the transmit status descriptor@the Access point, it shows , lots of "Tx delimiter under-run error" & " Tx data under-run error". Once the driver gets "under-run" error, it starts adjusting the Tx FIFO trigger level [TXCFG register, Frame Trigger level], and it finally reaches it's maximum. This register specifies the minimum number of bytes that must be DMAed into the PCU TXFIFO, before the PCU initiates the frame on the air. Any idea on why it's happening ?. Are we missing any special kind of configuration ?. Or is there any known issue when we enable both Aggregation (AMPDU) and encryption simultaneously ?. The same setup is working, if we disable the Encryption ( getting around 95.7 Mbps). Also the encryption alone is working, without the Aggregation, though we are getting a degraded performance ( max around 30 Mbps.) Thanks in advance, Mahesh.