Date: Tue, 12 May 2020 18:45:45 +0000 From: bugzilla-noreply@freebsd.org To: virtualization@FreeBSD.org Subject: [Bug 234838] ena drop-outs on 12.0-RELEASE Message-ID: <bug-234838-27103-f5BXCcRwyf@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-234838-27103@https.bugs.freebsd.org/bugzilla/> References: <bug-234838-27103@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D234838 --- Comment #23 from commit-hook@freebsd.org --- A commit references this bug: Author: mw Date: Tue May 12 18:44:41 UTC 2020 New revision: 360985 URL: https://svnweb.freebsd.org/changeset/base/360985 Log: MFC r360777: Optimize ENA Rx refill for low memory conditions Sometimes, especially when there is not much memory in the system left, allocating mbuf jumbo clusters (like 9KB or 16KB) can take a lot of time and it is not guaranteed that it'll succeed. In that situation, the fallback will work, but if the refill needs to take a place for a lot of descriptors at once, the time spent in m_getjcl looking for memory can cause system unresponsiveness due to high priority of the Rx task. This can also lead to driver reset, because Tx cleanup routine is being blocked and timer service could detect that Tx packets aren't cleaned up. The reset routine can further create another unresponsiveness - Rx rings are being refilled there, so m_getjcl will again burn the CPU. This was causing NVMe driver timeouts and resets, because network driver is having higher priority. Instead of 16KB jumbo clusters for the Rx buffers, 9KB clusters are enough - ENA MTU is being set to 9K anyway, so it's very unlikely that more space than 9KB will be needed. However, 9KB jumbo clusters can still cause issues, so by default the page size mbuf cluster will be used for the Rx descriptors. This can have= a small (~2%) impact on the throughput of the device, so to restore original behavior, one must change sysctl "hw.ena.enable_9k_mbufs" to "1" in "/boot/loader.conf" file. As a part of this patch (important fix), the version of the driver was updated to v2.1.2. Submitted by: cperciva PR: 225791, 234838, 235856, 236989, 243531 Changes: _U stable/12/ stable/12/sys/dev/ena/ena.c stable/12/sys/dev/ena/ena.h --=20 You are receiving this mail because: You are the assignee for the bug.=
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