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To: Uladzislau Rezki CC: Matthew Wilcox , , , , , , References: <20241203023159.219355-1-zuoze1@huawei.com> <57f9eca2-effc-3a9f-932b-fd37ae6d0f87@huawei.com> From: zuoze In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.186] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemg500008.china.huawei.com (7.202.181.45) X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: A7662180020 X-Stat-Signature: rp7arrbyie5fg9y68ushfdegmq34kqf8 X-Rspam-User: X-HE-Tag: 1733231409-95787 X-HE-Meta: U2FsdGVkX19ZMsPNBCU1hOtinMssPbrlgaSjbDOZraUNZ8W5wR1xfdt1yt5MZMkAAY3MFUfpyWZamQYR5Tdk19X6VrUTLO4g7NAUgKOorYoNnV1ZmgX1mykiuBKwZqDRvJpyJUfuHN6zJqgD1hu8tERc/5gxhe3XmaaS4Wftt1YNOWhh9coauNatk+kNhXBzM2EFL03IWMGIKbDuwFljDq+e4Bcl198I94vZbCMIAJk0xxuyLyfQEW79w2kxLigyWsEMkb5igOZXYR5GXjdE9lR5AlTgUbf3K1DYc2NhCu+LXVaXC1LeyrkRTeA/w6OPnJ3dBC2yfY1fIGMaOdmC1KTx6SE8waXNEo3PvTbErdiD8IL+lESVw9uCT1K0WUeGauAM2bMfDGLQWjbrbNFp341TQQajmSyzTXAwnVWe1VIO7mWNEm2VZMvjH1cVZkkSF9zslWt3YnMHyrBm2W8GtyNONHrBQZtkEs0Nwg2naccNwfA22YWWN9iESBFprS5UsRDlnsyRb4GFF3fyWHU36feG2qh7NX6r4PwuOGCuH6IF4Ayj//IKw+r0sVCwKWW/EIG7dJfb5mIpGNODdPllSpTVJllpNf4rdrOGSK3G31f6dHS9f3MLQzGO3GbRhx2+bmvKrCNIrpqJc6gjEM+4BdCA+M6Z20tqj1xY3PeRzb9Bce5cXd0QaD+Ps5x8aea0xNTGO2bjn3ggvDtleeRUHGo+mTiKxh79vcw3q28bhHNv1JA3h/O6Tb8LaLtxRaq/mBLh9YxUQW+s/JN6siw0ViT/DPHCEUlwaMjJvChnSBU4wL0KBQlgCPgOM2G47CavjibP5a+oeEzQ4Loi21JKllPh3HSKf5zbbiCL5ENF9KbQIVLmEMOPuGpt24Qs8GhHOIx60UYAcROxFgHVsORn1NlNK58TxPPXWeq5xP9iokLiK/mx/wYhKy8s6UGW5UT9OusNG9ptZM9YKi1+yJx MIf2Tx0E 891eu7DK1U0UCyKVqjMhStzpSKeghQD3GKrnQ2xdJqkwiwZm/QEBfu4uK0oat2vP4D7pZLVFmmCa02XomefC19zCdSN6WaMdWfIL2QAzgfxujyIqZG3aDDJuiW+qYeDlLSz3DuO/uSqcENLmEg/5or/dLn4g6g06ZHloMqoBuy+fIC64+iCKYJTycvsQ697jnJ89QeH+9ptBbvIbGKIEhjT4V3PVabxQYfVTHAchceMhq/LQ= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 在 2024/12/3 20:39, Uladzislau Rezki 写道: > On Tue, Dec 03, 2024 at 07:23:44PM +0800, zuoze wrote: >> We have implemented host-guest communication based on the TUN device >> using XSK[1]. The hardware is a Kunpeng 920 machine (ARM architecture), >> and the operating system is based on the 6.6 LTS version with kernel >> version 6.6. The specific stack for hotspot collection is as follows: >> >> - 100.00% 0.00% vhost-12384 [unknown] [k] 0000000000000000 >> - ret_from_fork >> - 99.99% vhost_task_fn >> - 99.98% 0xffffdc59f619876c >> - 98.99% handle_rx_kick >> - 98.94% handle_rx >> - 94.92% tun_recvmsg >> - 94.76% tun_do_read >> - 94.62% tun_put_user_xdp_zc >> - 63.53% __check_object_size >> - 63.49% __check_object_size.part.0 >> find_vmap_area >> - 30.02% _copy_to_iter >> __arch_copy_to_user >> - 2.27% get_rx_bufs >> - 2.12% vhost_get_vq_desc >> 1.49% __arch_copy_from_user >> - 0.89% peek_head_len >> 0.54% xsk_tx_peek_desc >> - 0.68% vhost_add_used_and_signal_n >> - 0.53% eventfd_signal >> eventfd_signal_mask >> - 0.94% handle_tx_kick >> - 0.94% handle_tx >> - handle_tx_copy >> - 0.59% vhost_tx_batch.constprop.0 >> 0.52% tun_sendmsg >> >> It can be observed that most of the overhead is concentrated in the >> find_vmap_area function. >> > I see. Yes, it is pretty contented, since you run the v6.6 kernel. There > was a work that tends to improve it to mitigate a vmap lock contention. > See it here: https://lwn.net/Articles/956590/ > > The work was taken in the v6.9 kernel: > > > commit 38f6b9af04c4b79f81b3c2a0f76d1de94b78d7bc > Author: Uladzislau Rezki (Sony) > Date: Tue Jan 2 19:46:23 2024 +0100 > > mm: vmalloc: add va_alloc() helper > > Patch series "Mitigate a vmap lock contention", v3. > > 1. Motivation > ... > > > Could you please try the v6.9 kernel on your setup? > > How to solve it, probably, it can be back-ported to the v6.6 kernel. All the vmalloc-related optimizations have already been merged into 6.6, including the set of optimization patches you suggested. Thank you very much for your input. > > Thanks! > > -- > Uladzislau Rezki > Thanks, ze zuo