Date: Thu, 7 Nov 2024 15:02:54 -0800 From: Bakul Shah <bakul@iitbombay.org> To: Mark Johnston <markj@freebsd.org> Cc: Andriy Gapon <avg@freebsd.org>, FreeBSD Net <freebsd-net@freebsd.org> Subject: Re: An interesting anomaly in NFS client... Message-ID: <872F2EE1-29F3-40E7-954D-3FFACD7C72D7@iitbombay.org> In-Reply-To: <Zy06kX6pJIuMzoFB@nuc> References: <7FFE3D2B-4DD9-4657-ADC1-9C40CB54991F@neville-neil.com> <8187509e-c9fb-403f-8569-28ba58425cff@FreeBSD.org> <Zy06kX6pJIuMzoFB@nuc>
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On Nov 7, 2024, at 2:09=E2=80=AFPM, Mark Johnston <markj@freebsd.org> = wrote: >=20 > On Thu, Nov 07, 2024 at 07:28:59AM +0200, Andriy Gapon wrote: >> On 07/11/2024 02:43, George Neville-Neil wrote: >>> Howdy, >>>=20 >>> We've been digging into an interesting possible issue in the FreeBSD = NFS >>> client. Here is the scenario. I have a FreeBSD VM on my Mac, the Mac = is >>> the NFS server, the VM is the client. I then attempt to build an out = of >>> tree kernel module that I'm working on. The build looks like it's >>> hanging for 1.5 seconds, and when we look at the packets (pcap file >>> attached) we see a ton of GETATTRs over the first 1.5 seconds. I've = put >>> the pcap up here: oct_8_2024.pcapng <https:// >>> people.freebsd.org/~gnn/oct_8_2024.pcapng> >>>=20 >>> I also note that an issue was raised on the forums that seems = similar, >>> way back between FreeBSD 10 and 11: >>>=20 >>> = https://forums.freebsd.org/threads/nfs-cache-misses-after-upgrading-to-11-= 1- >>> from-10-3.65491/ >>> <https://forums.freebsd.org/threads/nfs-cache-misses-after- >>> upgrading-to-11-1-from-10-3.65491/> >>>=20 >>> I'm seeing this on 15 currentish (last few months). >>=20 >> Could it be just make checking for stale targets? >> I.e., stat-ing various files to check their timestamps. >=20 > I suspect it is from this line in sys/conf/config.mk: >=20 > __MPATH!=3Dfind ${SYSDIR:tA}/ -name \*_if.m >=20 > This is running a find command over all of sys/, so it'll stat about > 35000 files. I believe it's from > = https://cgit.freebsd.org/src/commit/?id=3D12f05b84463baacfada5a79eaed061a4= 899d98aa At least for this find, p9fs (in freebsd vm) is about 20 times faster! No idea how well qemu's 9pfs works but worth a try.=
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