Date: Mon, 20 Aug 2012 16:06:56 +0530 From: "Jayachandran C." <c.jayachandran@gmail.com> To: Alan Cox <alc@rice.edu> Cc: mips@freebsd.org Subject: Re: mips pmap patch Message-ID: <CA%2B7sy7CK=EXu88XKYYXDV1uf3U7eebq3e6rfwgHRhQyFTMv7dQ@mail.gmail.com> In-Reply-To: <502D2271.6080105@rice.edu> References: <50228F5C.1000408@rice.edu> <CA%2B7sy7DxqhGhJt%2BwE3WW2-j4SxnPweULjYS5GQ=NgMYSrwJHtw@mail.gmail.com> <50269AD4.9050804@rice.edu> <CA%2B7sy7AZ-s2H6COfvz60N=kxw%2BWUiUC9diVfWg9aOzWSZKGWRQ@mail.gmail.com> <5029635A.4050209@rice.edu> <CA%2B7sy7Cnsy7Ag1iG=_Kj04gEXeYp7kZnpACQpD8THvkp0VKdcA@mail.gmail.com> <502D2271.6080105@rice.edu>
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On Thu, Aug 16, 2012 at 10:10 PM, Alan Cox <alc@rice.edu> wrote: > On 08/15/2012 17:21, Jayachandran C. wrote: >> >> On Tue, Aug 14, 2012 at 1:58 AM, Alan Cox<alc@rice.edu> wrote: >>> >>> On 08/13/2012 11:37, Jayachandran C. wrote: [...] >>>> I could not test for more than an hour on 32-bit due to another >>>> problem (freelist 1 containing direct-mapped pages runs out of pages >>>> after about an hour of compile test). This issue has been there for a >>>> long time, I am planning to look at it when I get a chance. >>>> >>> What exactly happens? panic? deadlock? >> >> The build slows down to a crawl and hangs when it runs out of pages in >> the freelist. > > > I'd like to see the output of "sysctl vm.phys_segs" and "sysctl > vm.phys_free" from this machine. Even better would be running "sysctl > vm.phys_free" every 60 seconds during the buildworld. Finally, I'd like to > know whether or not either "ps" or "top" shows any threads blocked on the > "swwrt" wait channel once things slow to a crawl. I spent some time looking at this issue. I use a very large kernel image with built-in root filesystem, and this takes about 120 MB out of the direct mapped area. The remaining pages (~64 MB) are not enough for the build process. If I increase free memory in this area either by reducing the rootfs size of by adding a few more memory segments to this area, the build goes through fine. I also found that when the build slows down, most of the pages taken from freelist 1 are allocated by the UMA subsystem, which seems to keep quite a few pages allocated. Regards, JC.
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