| Message ID | 1533825236-22896-2-git-send-email-asmadeus@codewreck.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3,1/2] net/9p: embed fcall in req to round down buffer allocs | expand |
Hi Dominique, Could you help paste the test result of before-after-applied this patch in comment? And please see my comments below. On 2018/8/9 22:33, Dominique Martinet wrote: > From: Dominique Martinet <dominique.martinet@cea.fr> > > Having a specific cache for the fcall allocations helps speed up > allocations a bit, especially in case of non-"round" msizes. > > The caches will automatically be merged if there are multiple caches > of items with the same size so we do not need to try to share a cache > between different clients of the same size. > > Since the msize is negotiated with the server, only allocate the cache > after that negotiation has happened - previous allocations or > allocations of different sizes (e.g. zero-copy fcall) are made with > kmalloc directly. > > Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Greg Kurz <groug@kaod.org> > Cc: Jun Piao <piaojun@huawei.com> > --- > v2: > - Add a pointer to the cache in p9_fcall to make sure a buffer > allocated with kmalloc gets freed with kfree and vice-versa > This could have been smaller with a bool but this spares having > to look at the client so looked a bit cleaner, I'm expecting this > patch will need a v3 one way or another so I went for the bolder > approach - please say if you think a smaller item is better ; I *think* > nothing relies on this being ordered the same way as the data on the > wire (struct isn't packed anyway) so we can move id after tag and add > another u8 to not have any overhead > > - added likely() to cache existence check in allocation, but nothing > for msize check or free because of zc request being of different size > > v3: > - defined the userdata region in the cache, as read or write calls can > access the buffer directly (lead to warnings with HARDENED_USERCOPY=y) > > > > I didn't get any comment on v2 for this patch, but I'm still not fully > happy with this in all honesty. > > Part of me believes we might be better off always allocating from the > cache even for zero-copy headers, it's a waste of space but the buffers > are there and being reused constantly for non-zc calls, and mixing > kmallocs in could lead to these buffers being really freed and > reallocated all the time instead of reusing the slab buffers > continuously. > > That would let me move the likely() for the fast path, with the only > exception being the TVERSION initial call on mount, for which I still > don't have any nice idea on how to handle, using a different size in > p9_client_rpc or prepare_req if the type is TVERSION and I'm really not > happy with that... > > > include/net/9p/9p.h | 4 ++++ > include/net/9p/client.h | 1 + > net/9p/client.c | 40 +++++++++++++++++++++++++++++++++++----- > 3 files changed, 40 insertions(+), 5 deletions(-) > > diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h > index e23896116d9a..645266b74652 100644 > --- a/include/net/9p/9p.h > +++ b/include/net/9p/9p.h > @@ -336,6 +336,9 @@ enum p9_qid_t { > #define P9_NOFID (u32)(~0) > #define P9_MAXWELEM 16 > > +/* Minimal header size: len + id + tag */ Here should be 'size + id + tag'. > +#define P9_HDRSZ 7 > + > /* ample room for Twrite/Rread header */ > #define P9_IOHDRSZ 24 > > @@ -558,6 +561,7 @@ struct p9_fcall { > size_t offset; > size_t capacity; > > + struct kmem_cache *cache; > u8 *sdata; > }; > > diff --git a/include/net/9p/client.h b/include/net/9p/client.h > index c2671d40bb6b..735f3979d559 100644 > --- a/include/net/9p/client.h > +++ b/include/net/9p/client.h > @@ -123,6 +123,7 @@ struct p9_client { > struct p9_trans_module *trans_mod; > enum p9_trans_status status; > void *trans; > + struct kmem_cache *fcall_cache; > > union { > struct { > diff --git a/net/9p/client.c b/net/9p/client.c > index ed78751aee7c..6c57ab1294d7 100644 > --- a/net/9p/client.c > +++ b/net/9p/client.c > @@ -192,6 +192,9 @@ static int parse_opts(char *opts, struct p9_client *clnt) > goto free_and_return; > } > > + if (clnt->trans_mod) { > + pr_warn("Had trans %s\n", clnt->trans_mod->name); > + } > v9fs_put_trans(clnt->trans_mod); > clnt->trans_mod = v9fs_get_trans_by_name(s); > if (clnt->trans_mod == NULL) { > @@ -231,9 +234,16 @@ static int parse_opts(char *opts, struct p9_client *clnt) > return ret; > } > > -static int p9_fcall_init(struct p9_fcall *fc, int alloc_msize) > +static int p9_fcall_init(struct p9_client *c, struct p9_fcall *fc, > + int alloc_msize) > { > - fc->sdata = kmalloc(alloc_msize, GFP_NOFS); > + if (likely(c->fcall_cache) && alloc_msize == c->msize) { > + fc->sdata = kmem_cache_alloc(c->fcall_cache, GFP_NOFS); > + fc->cache = c->fcall_cache; > + } else { > + fc->sdata = kmalloc(alloc_msize, GFP_NOFS); > + fc->cache = NULL; > + } > if (!fc->sdata) > return -ENOMEM; > fc->capacity = alloc_msize; > @@ -242,7 +252,16 @@ static int p9_fcall_init(struct p9_fcall *fc, int alloc_msize) > > void p9_fcall_fini(struct p9_fcall *fc) > { > - kfree(fc->sdata); > + /* sdata can be NULL for interrupted requests in trans_rdma, > + * and kmem_cache_free does not do NULL-check for us > + */ > + if (unlikely(!fc->sdata)) > + return; > + > + if (fc->cache) > + kmem_cache_free(fc->cache, fc->sdata); > + else > + kfree(fc->sdata); > } > EXPORT_SYMBOL(p9_fcall_fini); > > @@ -267,9 +286,9 @@ p9_tag_alloc(struct p9_client *c, int8_t type, unsigned int max_size) > if (!req) > return NULL; > > - if (p9_fcall_init(&req->tc, alloc_msize)) > + if (p9_fcall_init(c, &req->tc, alloc_msize)) > goto free_req; > - if (p9_fcall_init(&req->rc, alloc_msize)) > + if (p9_fcall_init(c, &req->rc, alloc_msize)) > goto free; > > p9pdu_reset(&req->tc); > @@ -951,6 +970,7 @@ struct p9_client *p9_client_create(const char *dev_name, char *options) > > clnt->trans_mod = NULL; > clnt->trans = NULL; > + clnt->fcall_cache = NULL; > > client_id = utsname()->nodename; > memcpy(clnt->name, client_id, strlen(client_id) + 1); > @@ -987,6 +1007,15 @@ struct p9_client *p9_client_create(const char *dev_name, char *options) > if (err) > goto close_trans; > > + /* P9_HDRSZ + 4 is the smallest packet header we can have that is > + * followed by data accessed from userspace by read > + */ > + clnt->fcall_cache = > + kmem_cache_create_usercopy("9p-fcall-cache", clnt->msize, > + 0, 0, P9_HDRSZ + 4, > + clnt->msize - (P9_HDRSZ + 4), > + NULL); > + > return clnt; > > close_trans: > @@ -1018,6 +1047,7 @@ void p9_client_destroy(struct p9_client *clnt) > > p9_tag_cleanup(clnt); > > + kmem_cache_destroy(clnt->fcall_cache); I'm afraid that we should check NULL for clnt->fcall_cache. Thanks, Jun > kfree(clnt); > } > EXPORT_SYMBOL(p9_client_destroy); >
piaojun wrote on Fri, Aug 10, 2018: > Could you help paste the test result of before-after-applied this patch in > comment? And please see my comments below. Thanks the the review, do you mean the commit message? I'll add the summary I wrote in reply to your question a few mails before. > > diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h > > index e23896116d9a..645266b74652 100644 > > --- a/include/net/9p/9p.h > > +++ b/include/net/9p/9p.h > > @@ -336,6 +336,9 @@ enum p9_qid_t { > > #define P9_NOFID (u32)(~0) > > #define P9_MAXWELEM 16 > > > > +/* Minimal header size: len + id + tag */ > > Here should be 'size + id + tag'. hm I didn't want to repeat size, but I guess people do refer to that field as size. I'll actually rewrite it as: Minimal header size: size[4] type[1] tag[2] > > + kmem_cache_destroy(clnt->fcall_cache); > > I'm afraid that we should check NULL for clnt->fcall_cache. kmem_cache_destroy() in mm/slab_common.c does the null check for us: ------ void kmem_cache_destroy(struct kmem_cache *s) { int err; if (unlikely(!s)) return; ------
Thanks for clearing my doubt, and you can add: Acked-by: Jun Piao <piaojun@huawei.com> On 2018/8/10 9:41, Dominique Martinet wrote: > piaojun wrote on Fri, Aug 10, 2018: >> Could you help paste the test result of before-after-applied this patch in >> comment? And please see my comments below. > > Thanks the the review, do you mean the commit message? > > I'll add the summary I wrote in reply to your question a few mails > before. > Yes, I mean the commit message. > >>> diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h >>> index e23896116d9a..645266b74652 100644 >>> --- a/include/net/9p/9p.h >>> +++ b/include/net/9p/9p.h >>> @@ -336,6 +336,9 @@ enum p9_qid_t { >>> #define P9_NOFID (u32)(~0) >>> #define P9_MAXWELEM 16 >>> >>> +/* Minimal header size: len + id + tag */ >> >> Here should be 'size + id + tag'. > > hm I didn't want to repeat size, but I guess people do refer to that > field as size. > I'll actually rewrite it as: > Minimal header size: size[4] type[1] tag[2] > It looks better. >>> + kmem_cache_destroy(clnt->fcall_cache); >> >> I'm afraid that we should check NULL for clnt->fcall_cache. > > kmem_cache_destroy() in mm/slab_common.c does the null check for us: > ------ > void kmem_cache_destroy(struct kmem_cache *s) > { > int err; > > if (unlikely(!s)) > return; > ------ > OK, it makes sense.
diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h index e23896116d9a..645266b74652 100644 --- a/include/net/9p/9p.h +++ b/include/net/9p/9p.h @@ -336,6 +336,9 @@ enum p9_qid_t { #define P9_NOFID (u32)(~0) #define P9_MAXWELEM 16 +/* Minimal header size: len + id + tag */ +#define P9_HDRSZ 7 + /* ample room for Twrite/Rread header */ #define P9_IOHDRSZ 24 @@ -558,6 +561,7 @@ struct p9_fcall { size_t offset; size_t capacity; + struct kmem_cache *cache; u8 *sdata; }; diff --git a/include/net/9p/client.h b/include/net/9p/client.h index c2671d40bb6b..735f3979d559 100644 --- a/include/net/9p/client.h +++ b/include/net/9p/client.h @@ -123,6 +123,7 @@ struct p9_client { struct p9_trans_module *trans_mod; enum p9_trans_status status; void *trans; + struct kmem_cache *fcall_cache; union { struct { diff --git a/net/9p/client.c b/net/9p/client.c index ed78751aee7c..6c57ab1294d7 100644 --- a/net/9p/client.c +++ b/net/9p/client.c @@ -192,6 +192,9 @@ static int parse_opts(char *opts, struct p9_client *clnt) goto free_and_return; } + if (clnt->trans_mod) { + pr_warn("Had trans %s\n", clnt->trans_mod->name); + } v9fs_put_trans(clnt->trans_mod); clnt->trans_mod = v9fs_get_trans_by_name(s); if (clnt->trans_mod == NULL) { @@ -231,9 +234,16 @@ static int parse_opts(char *opts, struct p9_client *clnt) return ret; } -static int p9_fcall_init(struct p9_fcall *fc, int alloc_msize) +static int p9_fcall_init(struct p9_client *c, struct p9_fcall *fc, + int alloc_msize) { - fc->sdata = kmalloc(alloc_msize, GFP_NOFS); + if (likely(c->fcall_cache) && alloc_msize == c->msize) { + fc->sdata = kmem_cache_alloc(c->fcall_cache, GFP_NOFS); + fc->cache = c->fcall_cache; + } else { + fc->sdata = kmalloc(alloc_msize, GFP_NOFS); + fc->cache = NULL; + } if (!fc->sdata) return -ENOMEM; fc->capacity = alloc_msize; @@ -242,7 +252,16 @@ static int p9_fcall_init(struct p9_fcall *fc, int alloc_msize) void p9_fcall_fini(struct p9_fcall *fc) { - kfree(fc->sdata); + /* sdata can be NULL for interrupted requests in trans_rdma, + * and kmem_cache_free does not do NULL-check for us + */ + if (unlikely(!fc->sdata)) + return; + + if (fc->cache) + kmem_cache_free(fc->cache, fc->sdata); + else + kfree(fc->sdata); } EXPORT_SYMBOL(p9_fcall_fini); @@ -267,9 +286,9 @@ p9_tag_alloc(struct p9_client *c, int8_t type, unsigned int max_size) if (!req) return NULL; - if (p9_fcall_init(&req->tc, alloc_msize)) + if (p9_fcall_init(c, &req->tc, alloc_msize)) goto free_req; - if (p9_fcall_init(&req->rc, alloc_msize)) + if (p9_fcall_init(c, &req->rc, alloc_msize)) goto free; p9pdu_reset(&req->tc); @@ -951,6 +970,7 @@ struct p9_client *p9_client_create(const char *dev_name, char *options) clnt->trans_mod = NULL; clnt->trans = NULL; + clnt->fcall_cache = NULL; client_id = utsname()->nodename; memcpy(clnt->name, client_id, strlen(client_id) + 1); @@ -987,6 +1007,15 @@ struct p9_client *p9_client_create(const char *dev_name, char *options) if (err) goto close_trans; + /* P9_HDRSZ + 4 is the smallest packet header we can have that is + * followed by data accessed from userspace by read + */ + clnt->fcall_cache = + kmem_cache_create_usercopy("9p-fcall-cache", clnt->msize, + 0, 0, P9_HDRSZ + 4, + clnt->msize - (P9_HDRSZ + 4), + NULL); + return clnt; close_trans: @@ -1018,6 +1047,7 @@ void p9_client_destroy(struct p9_client *clnt) p9_tag_cleanup(clnt); + kmem_cache_destroy(clnt->fcall_cache); kfree(clnt); } EXPORT_SYMBOL(p9_client_destroy);