Scanning the slot_to_gfn[] array for a free slot is expensive because
evict_pages() always needs to scan the whole array. Remember the last
slots freed during page-in requests and reuse them in evict_pages().
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Update functions to return -1 on error, 0 on success.
Simplify init_page() and make sure errno is assigned.
Adjust PERROR/ERROR usage, use PERROR early because it overwrites errno.
Adjust xenpaging_populate_page() to handle gfn as unsigned long.
Update xenpaging exit code handling. xenpaging_teardown cant possible
fail. Adjust mainloop to indicate possible errors to final exit.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
policy_choose_victim() is one of the bottlenecks in xenpaging. It is called
alot to find free bits in the fragmented bitmaps.
Reduce turnaround time by skipping longs with all bits set.
Adjust wrap detection in loop.
v2:
- fix copy&paste error, bitmap was tested twice
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Move all code to evict a single gfn into one function. This simplifies
error handling in caller. The function returns -1 on fatal error, 0 on
success and 1 if the gfn cant be paged.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Currently the command to flush the qemu cache is called alot if there
are no more pages to evict. This causes churn in the logfiles, and qemu
can not release more pages anyway since the last command.
Fix this by remembering the current number of paged-out gfns, if this
number did not change since the last flush command then sending another
new flush command will not free any more gfns.
Remove return code from xenpaging_mem_paging_flush_ioemu_cache() since
errors do not matter, and will be handled elsewhere. Also failure to
send the flush command is not fatal.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
The main loop calls xenpaging_wait_for_event_or_timeout() unconditionally
before doing any work. This function calls poll() with a timeout of 100ms. As
a result the page-out process is very slow due to the delay in poll().
Call poll() without timeout so that it returns immediately until the page-out
is done. Page-out is done when either the policy finds no more pages to
nominate or when the requested number of pages is reached.
The condition is cleared when a watch event arrives, so that processing the
new target is not delayed once again by poll().
v2:
- no poll timeout also when large number of evicts is pending
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
This change is based on an idea by <hongkaixing@huawei.com> and
<bicky.shi@huawei.com>.
Scanning the victims[] array is time consuming with a large number of
target pages. Replace the loop to find the slot in the pagefile which
holds the requested gfn with an index.
Remove the victims array and replace it with a flat array. This array
holds the gfn for a given slot in the pagefile. Adjust all users of the
victims array.
Rename variable in main() from i to slot to clearify the meaning.
Update xenpaging_evict_page() to pass a pointer to xen_pfn_t to
xc_map_foreign_pages().
Update policy_choose_victim() to return either a gfn or INVALID_MFN.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
If a page is nominated but not evicted,then dom0 accesses the page,it
will change the page's p2mt to be p2m_ram_paging_in,and the req.flags
is MEM_EVENT_FLAG_EVICT_FAIL;so it will fail in p2m_mem_paging_evict()
because of the p2mt;and paging->num_paged_out will not increase in
this case;After the paging process is terminated, the p2mt
p2m_ram_paging_in still remains in p2m table.Once domU accesses the
nominated page,it will result in BSOD or vm'stuck.
The patch adds the dealing of this request to resume the page before
xenpaging is ended.
[ This can happen if p2m_mem_paging_populate() was called by a foreign
domain. In this case MEM_EVENT_FLAG_VCPU_PAUSED is not set and xenpaging
will not sent a response. And in this case the ring is in an
inconsistent state anyway, new requests cant be added, I think. - Olaf ]
Signed-off-by: hongkaixing <hongkaixing@huawei.com>
Signed-off-by: shizhen <bicky.shi@huawei.com>
Acked-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
lseek() takes an off_t, the used "int << shiftsize" does not automatically
convert the int into a larger type. This leads to write errors with pagefiles
larger than 2G. Fix this by shifting an off_t instead of an int.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
The _XOPEN_SOURCE define was breaking the compilation under NetBSD.
I've removed it becasue it is not necessary.
Error message:
gcc -O1 -fno-omit-frame-pointer -m64 -g -fno-strict-aliasing
-std=gnu99 -Wall -Wstrict-prototypes -Wno-unused-value
-Wdeclaration-after-statement -D__XEN_TOOLS__ -MMD -MF
.xenpaging.o.d -fno-optimize-sibling-calls
-I/root/xen-04102011/tools/xenpaging/../../tools/libxc
-I/root/xen-04102011/tools/xenpaging/../../tools/include
-I/root/xen-04102011/tools/xenpaging/../../tools/xenstore
-I/root/xen-04102011/tools/xenpaging/../../tools/include -Werror
-Wno-unused -g -c -o xenpaging.o xenpaging.c -I/usr/xen42/include
-I/usr/include
cc1: warnings being treated as errors
xenpaging.c: In function 'xenpaging_init':
xenpaging.c:333: warning: implicit declaration of function 'asprintf'
Signed-off-by: Roger Pau Monne <roger.pau@entel.upc.edu>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
Without this change it is not possible to page-out all guest pages, then
trigger a page-in for all pages, and then page-out everything once
again. All pages in the mru list can not be paged out because they
remain active in the internal bitmap of paged pages.
Use the mru list only if the number of paged-out pages is larger than
the mru list. If the number is smaller, start to clear the mru list. In
case the number of paged-out pages drops to zero the mru list and the
internal bitmap will be empty as well.
Also add a new interface for dropped pages. If a gfn was dropped there
is no need to adjust the mru list because dropping a page is not usage
of a page.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Introduce a cmdline handling for the pager. This simplifies libxl support,
debug and mru_size are not passed via the environment anymore.
The new interface looks like this:
xenpaging [options] -f <pagefile> -d <domain_id>
options:
-d <domid> --domain=<domid> numerical domain_id of guest. This option is required.
-f <file> --pagefile=<file> pagefile to use. This option is required.
-m <max_memkb> --max_memkb=<max_memkb> maximum amount of memory to handle.
-r <num> --mru_size=<num> number of paged-in pages to keep in memory.
-d --debug enable debug output.
-h --help this output.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Subsequent patches will use xenstored to store the numbers of pages
xenpaging is suppose to page-out.
Remove num_pages and use target_pages instead.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
This change reverses the task of xenpaging. Before this change a fixed number
of pages was paged out. With this change the guest will not have access to
more than the given number of pages at the same time.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
In preparation of upcoming libxl integration,
move xenpaging binary from /usr/sbin/ to /usr/lib/xen/bin/
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Nomination of gfns can fail, but may succeed later.
Thats the case for a guest that starts ballooned.
v2:
- print debug when clearing uncosumed happens
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Remove the if/else logic to exit from the in case a signal arrives.
Update comments.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Move page resume loop into its own function.
Move page eviction loop into its own function.
Allocate all possible slots in a paging file to allow growing and
shrinking of the number of paged-out pages. Adjust other places to
iterate over all slots.
This change is required by subsequent patches.
v2:
- check if victims allocation succeeded
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Remove xc_dominfo_t from paging_t, record only max_pages.
This value is used to setup internal data structures.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Move comment about xc_handle to the right place.
Allocate paging early and use calloc.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Catch lseek() errors.
Use -1 as return value and let caller read errno.
Remove const casts from buffer pointers, the page is writeable.
Use wrapper for write() which matches the read() prototype.
Remove unused stdarg.h inclusion.
Remove unused macro.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
v3:
- adjust arguments for xc_mem_paging_enable() failures
v2:
- move changes to file_op() to different patch
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Remove stale comment.
If a page was populated several times the vcpu is paused and
xenpaging has to unpause it again.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Create two new variables called APPEND_ and PREPEND_ to add compile
flags at the beginning or at the end of the search path.
Added a new semantic for user defined compile flags, here is the list
of possible options:
PREPEND_LIB: add libraries to the search path before xen
(before xen installation folders).
PREPEND_INCLUDES: add headers to the search path before xen
(before xen installation folders).
APPEND_LIB: add libraries to the search path at the end
(after all xen installation folders have been added).
APPEND_INCLUDES: add libraries to the search path at the end
(after all xen installation folders have been added).
EXTRA_INCLUDES and EXTRA_LIB can still be used, and they will have the
same effect as PREPEND_INCLUDES and PREPEND_LIB.
Signed-off-by: Roger Pau Monne <roger.pau@entel.upc.edu>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
Do munmap() on all mapped pages, not just the first one. Without this
change the gfns backing the remaining pages can not be paged out again
because the page count does not go down to 1. This change was missing
from changeset 23827:d1d6abc1db20.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
Disallow xenpaging in a PoD guest until coexistance between the two features
is properly implemented.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Tim Deegan <tim@xen.org>
Committed-by: Tim Deegan <tim@xen.org>
Evict of a nominated gfn must fail if some other process mapped the
page without checking the p2mt of that gfn first.
Add a check to cancel eviction if the page usage count is not 1.
Handle the possible eviction failure in the page-in paths.
After nominate and before evict, something may check the p2mt and call
populate. Handle this case and let the gfn enter the page-in path. The
gfn may still be connected to a mfn, so there is no need to allocate a
new page in prep.
Adjust do_mmu_update to return -ENOENT only if the gfn has entered the
page-in path and if it is not yet connected to a mfn. Otherwise
linux_privcmd_map_foreign_bulk() may loop forever.
Add MEM_EVENT_FLAG_EVICT_FAIL to inform pager that a page-in request for
a possible not-evicted page was sent. xenpaging does currently not need
that flag because failure to evict a gfn will be caught.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Tim Deegan <tim@xen.org>
Committed-by: Tim Deegan <tim@xen.org>
If the guest happens to read from the gfn while xenpaging is in the process of
evicting the page, the guest may read zeros instead of actual data.
Also if eviction fails the page content will be corrupted and xenpaging wont
attempt to restore the page.
Remove page scrubbing from pager and do it after successful eviction.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Tim Deegan <tim@xen.org>
Committed-by: Tim Deegan <tim@xen.org>
Up to now a single ring buffer was used for mem_share, xenpaging and
xen-access. Each helper would have to cooperate and pull only its own
requests from the ring. Unfortunately this was not implemented. And
even if it was, it would make the whole concept fragile because a crash
or early exit of one helper would stall the others.
What happend up to now is that active xenpaging + memory_sharing would
push memsharing requests in the buffer. xenpaging is not prepared for
such requests.
This patch creates an independet ring buffer for mem_share, xenpaging
and xen-access and adds also new functions to enable xenpaging and
xen-access. The xc_mem_event_enable/xc_mem_event_disable functions will
be removed. The various XEN_DOMCTL_MEM_EVENT_* macros were cleaned up.
Due to the removal the API changed, so the SONAME will be changed too.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Tim Deegan <tim@xen.org>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Tim Deegan <tim@xen.org>
tools/xenpaging/mem_event.h is only included in xenpaging.h.
Add the contents into that file and remove mem_event.h.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Write all paged-out pages back into the guest if the pager is
interrupted by ctrl-c or if it receives SIGTERM.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
If xenpaging is started manually then no event is sent to xenpaging when
the guest is shutdown or rebooted. Add a watch on the @releaseDomain
node to leave the loop and gracefully shutdown the pager.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Unlink pagefile in the signal handler and also in the exit path.
This does not leave a stale pagefile if an error occoured.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Pass gfn as integer to xenpaging_populate_page(). xc_map_foreign_pages()
takes a pointer to a list of gfns, but its a const pointer. So writing
the value back to the caller is not needed.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Set the starting gfn to somewhere in the middle of the gfn range to
avoid paging during BIOS startup. This can speedup booting of a guest.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Olaf Hering
Roger Pau Monne
Andres Lagar-Cavilla
Tim Deegan