[Bug translator/6008] New: support larger on-memory buffer

[Bug translator/6008] New: support larger on-memory buffer

[mhiramat at redhat dot com]

systemtap allows users to allocate more memories (ex. 2GB) for trace buffers
which can keep the trace data for a longer time on main memory.

Current trace buffer size is limited less than 64 MB per cpu even if we have a
plenty of memory (tens of GB) and a large memory space in kernel(especially
64bit arch). Therefore, we aren't able to log trace data for long enough.

Current limitation comes from relayfs which allocates an array of (struct page*)
for total allocating pages by kmalloc. However, usually, since the size of
kmalloc is limited, relayfs can not allocate the array if specified buffer size
is over (max_kmalloc_size/sizeof(struct page*))*page_size (=128KB/8B*4KB = 64MB
on x86-64). So, I think we can solve this by using vmalloc instead of kmalloc
when the array size is over one page_size.

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           Summary: support larger on-memory buffer
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: translator
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: mhiramat at redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=6008

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[Bug translator/6008] support larger on-memory buffer

[mhiramat at redhat dot com]

------- Additional Comments From mhiramat at redhat dot com  2008-04-08 20:33 -------
Created an attachment (id=2634)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=2634&action=view)
remove the size limitation of buffer

This patch removes current 64MB upper limitation from systemtap.


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6008

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[Bug translator/6008] support larger on-memory buffer

[mhiramat at redhat dot com]

------- Additional Comments From mhiramat at redhat dot com  2008-04-08 20:36 -------
Created an attachment (id=2648)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=2648&action=view)
relayfs patch: use vmalloc to allocate *page array

with this patch, relayfs uses vmalloc to allocate *page array if the array is
bigger than one page, otherwise, it uses kcalloc.


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6008

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[Bug translator/6008] support larger on-memory buffer

[mhiramat at redhat dot com]

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  BugsThisDependsOn|                            |5645


http://sourceware.org/bugzilla/show_bug.cgi?id=6008

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