[haiku-bugs] Re: [Haiku] #5777: Kernel starts paging when writing to slow media
- From: "bonefish" <trac@xxxxxxxxxxxx>
- Date: Thu, 30 Jan 2014 11:01:18 -0000
#5777: Kernel starts paging when writing to slow media
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Reporter: axeld | Owner: axeld
Type: bug | Status: assigned
Priority: normal | Milestone: R1/beta1
Component: System/Kernel | Version: R1/Development
Resolution: | Keywords:
Blocked By: | Blocking:
Has a Patch: 0 | Platform: All
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Comment (by bonefish):
@pulkomandy: The symptoms you are observing probably aren't even related
to the original bug, but since no one has really attached any information
so far it is hard to tell. The ticket description refers to large files
while you are copying many files. I believe your memory usage statistics
actually mean that not a lot of memory is used, save for a bit of file
cache, which should be subsumed under "cache memory". The low resource in
your case is probably kernel address space (the syslog would say). The
rather small "block cache" value supports that assumption (the low
resource manager is pushing the block cache to free up address space).
FWIW, I saw a similar/the same issue at the last BeGeistert on Olivier's
machine. Since I already worked on another bug I didn't dig too deep, but
I saw that a lot of address space was used for the physical page mapper.
My theory is that page mapper slots are leaked. The code Michael
introduced to improve I/O scheduling support for USB (hrev33523,
hrev33524, hrev33525, hrev33526) has some issues (cf. my TODOs
[http://cgit.haiku-
os.org/haiku/tree/src/system/kernel/device_manager/IORequest.cpp#n117
here] and [http://cgit.haiku-
os.org/haiku/tree/src/system/kernel/vm/vm.cpp#n1667 here]) which might
actually be responsible. But this needs closer examination.
Anyway, this should go in a new ticket and it should be checked whether
the original issue of this ticket still exists.
--
Ticket URL: <https://dev.haiku-os.org/ticket/5777#comment:10>
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