On Wed, Jun 15, 2011 at 02:59:33PM -0700, Dan Magenheimer wrote:
> (Resending, just noticed I left xen-devel off the list.)
>
> Hi Konrad (and any others interested in reviewing) --
>
> This patch provides Linux kernel changes to drivers/xen/tmem.c
> (and drivers/xen build files) for the Xen tmem shim to support
> frontswap. It builds successfully even if the frontswap patchset
> is not present, so is suitable for merging in an upstream
> tree that has the cleancache patchset but does not yet have
> the frontswap patchset.
This is a quite small file.. This is it?
>
> Note that minor variations of this code have been posted and
> working with Xen tmem for 2-1/2 years, but the code was left
> behind when cleancache was split off to "divide and conquer"
> for upstream submission.
>
> I believe this patch supercedes the patch proposed in the
> xen-devel thread titled:
>
> [PATCH] xen-tmem: Build cleancache shim to Xen Transcendent Memory
> only if Cleancache is enabled
>
> For your convenience, the patch is also attached and in the
> following git branch:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/djm/tmem.git#stable/frontswap-tmemonly
>
> (since 3.0-rc1)
>
> drivers/xen/Kconfig | 7 ++
> drivers/xen/Makefile | 2 +-
> drivers/xen/tmem.c | 168
> ++++++++++++++++++++++++++++++++++++++++++++++----
> 3 files changed, 164 insertions(+), 13 deletions(-)
>
> Signed-off-by: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>
>
> Thanks,
> Dan
>
> diff -Napur linux-3.0-rc1/drivers/xen/Kconfig
> linux-3.0-rc1-frontswap-tmemonly/drivers/xen/Kconfig
> --- linux-3.0-rc1/drivers/xen/Kconfig 2011-05-29 18:43:36.000000000 -0600
> +++ linux-3.0-rc1-frontswap-tmemonly/drivers/xen/Kconfig 2011-06-14
> 10:44:20.091857809 -0600
> @@ -105,4 +105,11 @@ config SWIOTLB_XEN
> depends on PCI
> select SWIOTLB
>
> +config XEN_TMEM
> + bool
> + default y if (CLEANCACHE || FRONTSWAP)
> + help
> + Shim to interface in-kernel Transcendent Memory hooks
> + (e.g. cleancache and frontswap) to Xen tmem hypercalls.
> +
> endmenu
> diff -Napur linux-3.0-rc1/drivers/xen/Makefile
> linux-3.0-rc1-frontswap-tmemonly/drivers/xen/Makefile
> --- linux-3.0-rc1/drivers/xen/Makefile 2011-05-29 18:43:36.000000000
> -0600
> +++ linux-3.0-rc1-frontswap-tmemonly/drivers/xen/Makefile 2011-06-14
> 10:41:16.508856401 -0600
> @@ -1,6 +1,5 @@
> obj-y += grant-table.o features.o events.o manage.o balloon.o
> obj-y += xenbus/
> -obj-y += tmem.o
>
> nostackp := $(call cc-option, -fno-stack-protector)
> CFLAGS_features.o := $(nostackp)
> @@ -15,6 +14,7 @@ obj-$(CONFIG_XEN_GRANT_DEV_ALLOC) += xen
> obj-$(CONFIG_XENFS) += xenfs/
> obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o
> obj-$(CONFIG_XEN_PLATFORM_PCI) += xen-platform-pci.o
> +obj-$(CONFIG_XEN_TMEM) += tmem.o
> obj-$(CONFIG_SWIOTLB_XEN) += swiotlb-xen.o
> obj-$(CONFIG_XEN_DOM0) += pci.o
>
> diff -Napur linux-3.0-rc1/drivers/xen/tmem.c
> linux-3.0-rc1-frontswap-tmemonly/drivers/xen/tmem.c
> --- linux-3.0-rc1/drivers/xen/tmem.c 2011-05-29 18:43:36.000000000 -0600
> +++ linux-3.0-rc1-frontswap-tmemonly/drivers/xen/tmem.c 2011-06-14
> 16:34:23.487854177 -0600
> @@ -1,7 +1,7 @@
> /*
> * Xen implementation for transcendent memory (tmem)
> *
> - * Copyright (C) 2009-2010 Oracle Corp. All rights reserved.
> + * Copyright (C) 2009-2011 Oracle Corp. All rights reserved.
> * Author: Dan Magenheimer
> */
>
> @@ -9,8 +9,14 @@
> #include <linux/types.h>
> #include <linux/init.h>
> #include <linux/pagemap.h>
> +#include <linux/module.h>
> #include <linux/cleancache.h>
>
> +/* temporary ifdef until include/linux/frontswap.h is upstream */
> +#ifdef CONFIG_FRONTSWAP
> +#include <linux/frontswap.h>
> +#endif
> +
> #include <xen/xen.h>
> #include <xen/interface/xen.h>
> #include <asm/xen/hypercall.h>
> @@ -122,14 +128,8 @@ static int xen_tmem_flush_object(u32 poo
> return xen_tmem_op(TMEM_FLUSH_OBJECT, pool_id, oid, 0, 0, 0, 0, 0);
> }
>
> -static int xen_tmem_destroy_pool(u32 pool_id)
> -{
> - struct tmem_oid oid = { { 0 } };
> -
> - return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, oid, 0, 0, 0, 0, 0);
> -}
> -
> -int tmem_enabled;
> +int tmem_enabled __read_mostly;
> +EXPORT_SYMBOL(tmem_enabled);
>
> static int __init enable_tmem(char *s)
> {
> @@ -139,6 +139,14 @@ static int __init enable_tmem(char *s)
>
> __setup("tmem", enable_tmem);
>
> +#ifdef CONFIG_CLEANCACHE
> +static int xen_tmem_destroy_pool(u32 pool_id)
> +{
> + struct tmem_oid oid = { { 0 } };
> +
> + return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, oid, 0, 0, 0, 0, 0);
> +}
> +
> /* cleancache ops */
>
> static void tmem_cleancache_put_page(int pool, struct cleancache_filekey key,
> @@ -240,18 +248,154 @@ static struct cleancache_ops tmem_cleanc
> .init_shared_fs = tmem_cleancache_init_shared_fs,
> .init_fs = tmem_cleancache_init_fs
> };
> +#endif
>
> -static int __init xen_tmem_init(void)
> +#ifdef CONFIG_FRONTSWAP
> +/* frontswap tmem operations */
> +
> +/* a single tmem poolid is used for all frontswap "types" (swapfiles) */
> +static int tmem_frontswap_poolid;
> +
> +/*
> + * Swizzling increases objects per swaptype, increasing tmem concurrency
> + * for heavy swaploads. Later, larger nr_cpus -> larger SWIZ_BITS
> + */
> +#define SWIZ_BITS 4
> +#define SWIZ_MASK ((1 << SWIZ_BITS) - 1)
> +#define _oswiz(_type, _ind) ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
> +#define iswiz(_ind) (_ind >> SWIZ_BITS)
> +
> +static inline struct tmem_oid oswiz(unsigned type, u32 ind)
> +{
> + struct tmem_oid oid = { .oid = { 0 } };
> + oid.oid[0] = _oswiz(type, ind);
> + return oid;
> +}
> +
> +/* returns 0 if the page was successfully put into frontswap, -1 if not */
> +static int tmem_frontswap_put_page(unsigned type, pgoff_t offset,
> + struct page *page)
Hm, not aligned?
> +{
> + u64 ind64 = (u64)offset;
> + u32 ind = (u32)offset;
> + unsigned long pfn = page_to_pfn(page);
> + int pool = tmem_frontswap_poolid;
> + int ret;
> +
> + if (pool < 0)
> + return -1;
> + if (ind64 != ind)
> + return -1;
> + mb(); /* ensure page is quiescent; tmem may address it with an alias */
> + ret = xen_tmem_put_page(pool, oswiz(type, ind), iswiz(ind), pfn);
> + /* translate Xen tmem return values to linux semantics */
> + if (ret == 1)
> + return 0;
> + else
> + return -1;
This could be just : return (ret == 1) ? 0 : -1;
> +}
> +
> +/* returns 0 if the page was successfully gotten from frontswap, -1 if
> + * was not present (should never happen!) */
> +static int tmem_frontswap_get_page(unsigned type, pgoff_t offset,
> + struct page *page)
Ditto
> +{
> + u64 ind64 = (u64)offset;
> + u32 ind = (u32)offset;
> + unsigned long pfn = page_to_pfn(page);
> + int pool = tmem_frontswap_poolid;
> + int ret;
> +
> + if (pool < 0)
> + return -1;
> + if (ind64 != ind)
> + return -1;
This looks to repeat itself in the previous function. You might want to
make this a macro. Or a short inline function in the header file.
> + ret = xen_tmem_get_page(pool, oswiz(type, ind), iswiz(ind), pfn);
> + /* translate Xen tmem return values to linux semantics */
> + if (ret == 1)
> + return 0;
> + else
> + return -1;
Ditto.
> +}
> +
> +/* flush a single page from frontswap */
> +static void tmem_frontswap_flush_page(unsigned type, pgoff_t offset)
> +{
> + u64 ind64 = (u64)offset;
> + u32 ind = (u32)offset;
> + int pool = tmem_frontswap_poolid;
> +
> + if (pool < 0)
> + return;
> + if (ind64 != ind)
> + return;
> + (void) xen_tmem_flush_page(pool, oswiz(type, ind), iswiz(ind));
> +}
> +
> +/* flush all pages from the passed swaptype */
> +static void tmem_frontswap_flush_area(unsigned type)
> +{
> + int pool = tmem_frontswap_poolid;
> + int ind;
> +
> + if (pool < 0)
> + return;
> + for (ind = SWIZ_MASK; ind >= 0; ind--)
> + (void)xen_tmem_flush_object(pool, oswiz(type, ind));
> +}
> +
> +static void tmem_frontswap_init(unsigned ignored)
> {
> - struct cleancache_ops old_ops;
> + struct tmem_pool_uuid private = TMEM_POOL_PRIVATE_UUID;
> +
> + /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
> + if (tmem_frontswap_poolid < 0)
> + tmem_frontswap_poolid =
> + xen_tmem_new_pool(private, TMEM_POOL_PERSIST, PAGE_SIZE);
> +}
> +
> +static int use_frontswap = 1;
You could save some precious bytes by making this __initdata
Also the naming is different. You have tmem_enabled. How about
frontswap_enabled instead?
> +
> +static int __init no_frontswap(char *s)
> +{
> + use_frontswap = 0;
> + return 1;
This looks like you are using spaces instead of tabs. But it
could be the editor of mine mugling things up.
> +}
>
> +__setup("nofrontswap", no_frontswap);
> +
> +static struct frontswap_ops tmem_frontswap_ops = {
> + .put_page = tmem_frontswap_put_page,
> + .get_page = tmem_frontswap_get_page,
> + .flush_page = tmem_frontswap_flush_page,
> + .flush_area = tmem_frontswap_flush_area,
> + .init = tmem_frontswap_init
Ditto.
> +};
> +#endif
> +
> +static int __init xen_tmem_init(void)
> +{
> if (!xen_domain())
> return 0;
> +#ifdef CONFIG_FRONTSWAP
> + if (tmem_enabled && use_frontswap) {
> + char *s = "";
> + struct frontswap_ops old_ops =
> + frontswap_register_ops(&tmem_frontswap_ops);
> +
> + tmem_frontswap_poolid = -1;
> + if (old_ops.init != NULL)
> + s = " (WARNING: frontswap_ops overridden)";
> + printk(KERN_INFO "frontswap enabled, RAM provided by "
> + "Xen Transcendent Memory\n");
> + }
> +#endif
> #ifdef CONFIG_CLEANCACHE
> BUG_ON(sizeof(struct cleancache_filekey) != sizeof(struct tmem_oid));
> if (tmem_enabled && use_cleancache) {
> char *s = "";
> - old_ops = cleancache_register_ops(&tmem_cleancache_ops);
> + struct cleancache_ops old_ops =
> + cleancache_register_ops(&tmem_cleancache_ops);
> if (old_ops.init_fs != NULL)
> s = " (WARNING: cleancache_ops overridden)";
> printk(KERN_INFO "cleancache enabled, RAM provided by "
>
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