Bug 63531
| Summary: | Disabling in-memory write cache for x86-64 | ||
|---|---|---|---|
| Product: | Memory Management | Reporter: | Artem S. Tashkinov (aros) |
| Component: | Other | Assignee: | Andrew Morton (akpm) |
| Status: | CLOSED INVALID | ||
| Severity: | normal | CC: | alan |
| Priority: | P1 | ||
| Hardware: | x86-64 | ||
| OS: | Linux | ||
| Kernel Version: | 3.11 | Subsystem: | |
| Regression: | No | Bisected commit-id: | |
| Attachments: | 3.11 configuration | ||
Not a support forum A bug which causes serious stalls can hardly be called an attempt at turning a bugzilla into a support forum, Alan. The way you close bug reports is often user hostile to put it humbly. At least, you could give a link to a discussion which spans over 50 messages right now, and where Linus himself admits that the way dirty buffers are set up on x86-64 is not exactly the right way given today's RAM sizes. If anyone ever stumbles upon this bug report, please, read this discussion: http://linux-kernel.2935.n7.nabble.com/Disabling-in-memory-write-cache-for-x86-64-in-Linux-II-td742553.html or here http://comments.gmane.org/gmane.linux.kernel.mm/108708 A quick sane solution is to set sysctl variables this way: vm.dirty_background_bytes=33554432 vm.dirty_bytes=134217728 |
Created attachment 112021 [details] 3.11 configuration On my x86-64 PC (Intel Core i5 2500, 16GB RAM), I have the same 3.11 kernel built for the i686 (with PAE) and x86-64 architectures. What's really troubling me is that the x86-64 kernel has the following problem: When I copy large files to any storage device, be it my HDD with ext4 partitions or flash drive with a FAT32 partition, the kernel first caches them in memory entirely then flushes them some time later (quite unpredictably though) or immediately upon running "sync". How can I disable this in-memory cache altogether? When running the i686 kernel with the same configuration I don't observe this effect - files get written out almost immediately (for instance "sync" takes less than a second, whereas on x86-64 it can take a dozen of minutes depending on a file size and storage performance). I'm _not_ talking about disabling write cache on my storage itself (hdparm -W 0 /dev/XXX)- firstly this command is detrimental to the performance of my PC, secondly, it won't help in this instance. Swap is totally disabled, usually my memory is entirely free. Please, advise.